The documentation for the New-UnifiedGroup cmdlet (which creates a new Microsoft 365 Group) says that:
“You can specify multiple owners separated by commas.“
In other words, you should be able to say:
New-UnifiedGroup -Alias MyGroup -DisplayName "My Group" -Owner "Tony@Office365itpros.com", "Paul@Office365itpros.com"
But you can’t. PowerShell responds with:
Cannot process argument transformation on parameter ‘Owner’. Cannot convert the “System.Collections.ArrayList” value of type “System.Collections.ArrayList” to type “Microsoft.Exchange.Configuration.Tasks.RecipientIdParameter”. + CategoryInfo : InvalidData: (:) [New-UnifiedGroup], ParameterBindin…mationException + FullyQualifiedErrorId : ParameterArgumentTransformationError,New-UnifiedGroup + PSComputerName : outlook.office365.com
Which is all very nice. It seems like the documentation assumed that the ability of the cmdlet to process multiple members when it creates a new group extended to owners.
The WorkAround
Fortunately, two simple workaround exist. First, you can add multiple owners by specifying them in the ManagedBy parameters. In this example
You can see that I have specified both the Owner and ManagedBy parameter. If you don’t pass a value in Owner, Exchange Online sets the signed in user as a group owner along with the people specified in ManagedBy. In other words, make sure you use the right combination of parameters to add the people you want to be group owners.
The second method is to create the new group with New-UnifiedGroup and then add as many owners as you want with Add-UnifiedGroupLinks. Just make sure that the people you add as owners are first added as members because a group owner has to be a member before they can become an owner. So the commands are something like this:
Remember too that the link you pass must be something that Exchange Online can resolve. This can be a mailbox alias, primary SMTP address, display name, or even distinguished name.
For more information about using PowerShell to manage Office 365 Groups, see Chapter 14 of Office 365 for IT Pros.
{"id":null,"mode":"button","open_style":"in_modal","currency_code":"EUR","currency_symbol":"\u20ac","currency_type":"decimal","blank_flag_url":"https:\/\/office365itpros.com\/wp-content\/plugins\/tip-jar-wp\/\/assets\/images\/flags\/blank.gif","flag_sprite_url":"https:\/\/office365itpros.com\/wp-content\/plugins\/tip-jar-wp\/\/assets\/images\/flags\/flags.png","default_amount":100,"top_media_type":"featured_image","featured_image_url":"https:\/\/office365itpros.com\/wp-content\/uploads\/2022\/11\/cover-141x200.jpg","featured_embed":"","header_media":null,"file_download_attachment_data":null,"recurring_options_enabled":true,"recurring_options":{"never":{"selected":true,"after_output":"One time only"},"weekly":{"selected":false,"after_output":"Every week"},"monthly":{"selected":false,"after_output":"Every month"},"yearly":{"selected":false,"after_output":"Every year"}},"strings":{"current_user_email":"","current_user_name":"","link_text":"Virtual Tip Jar","complete_payment_button_error_text":"Check info and try again","payment_verb":"Pay","payment_request_label":"Office 365 for IT Pros","form_has_an_error":"Please check and fix the errors above","general_server_error":"Something isn't working right at the moment. Please try again.","form_title":"Office 365 for IT Pros","form_subtitle":null,"currency_search_text":"Country or Currency here","other_payment_option":"Other payment option","manage_payments_button_text":"Manage your payments","thank_you_message":"Thank you for supporting the work of Office 365 for IT Pros!","payment_confirmation_title":"Office 365 for IT Pros","receipt_title":"Your Receipt","print_receipt":"Print Receipt","email_receipt":"Email Receipt","email_receipt_sending":"Sending receipt...","email_receipt_success":"Email receipt successfully sent","email_receipt_failed":"Email receipt failed to send. Please try again.","receipt_payee":"Paid to","receipt_statement_descriptor":"This will show up on your statement as","receipt_date":"Date","receipt_transaction_id":"Transaction ID","receipt_transaction_amount":"Amount","refund_payer":"Refund from","login":"Log in to manage your payments","manage_payments":"Manage Payments","transactions_title":"Your Transactions","transaction_title":"Transaction Receipt","transaction_period":"Plan Period","arrangements_title":"Your Plans","arrangement_title":"Manage Plan","arrangement_details":"Plan Details","arrangement_id_title":"Plan ID","arrangement_payment_method_title":"Payment Method","arrangement_amount_title":"Plan Amount","arrangement_renewal_title":"Next renewal date","arrangement_action_cancel":"Cancel Plan","arrangement_action_cant_cancel":"Cancelling is currently not available.","arrangement_action_cancel_double":"Are you sure you'd like to cancel?","arrangement_cancelling":"Cancelling Plan...","arrangement_cancelled":"Plan Cancelled","arrangement_failed_to_cancel":"Failed to cancel plan","back_to_plans":"\u2190 Back to Plans","update_payment_method_verb":"Update","sca_auth_description":"Your have a pending renewal payment which requires authorization.","sca_auth_verb":"Authorize renewal payment","sca_authing_verb":"Authorizing payment","sca_authed_verb":"Payment successfully authorized!","sca_auth_failed":"Unable to authorize! Please try again.","login_button_text":"Log in","login_form_has_an_error":"Please check and fix the errors above","uppercase_search":"Search","lowercase_search":"search","uppercase_page":"Page","lowercase_page":"page","uppercase_items":"Items","lowercase_items":"items","uppercase_per":"Per","lowercase_per":"per","uppercase_of":"Of","lowercase_of":"of","back":"Back to plans","zip_code_placeholder":"Zip\/Postal Code","download_file_button_text":"Download File","input_field_instructions":{"tip_amount":{"placeholder_text":"How much would you like to tip?","initial":{"instruction_type":"normal","instruction_message":"How much would you like to tip? Choose any currency."},"empty":{"instruction_type":"error","instruction_message":"How much would you like to tip? Choose any currency."},"invalid_curency":{"instruction_type":"error","instruction_message":"Please choose a valid currency."}},"recurring":{"placeholder_text":"Recurring","initial":{"instruction_type":"normal","instruction_message":"How often would you like to give this?"},"success":{"instruction_type":"success","instruction_message":"How often would you like to give this?"},"empty":{"instruction_type":"error","instruction_message":"How often would you like to give this?"}},"name":{"placeholder_text":"Name on Credit Card","initial":{"instruction_type":"normal","instruction_message":"Enter the name on your card."},"success":{"instruction_type":"success","instruction_message":"Enter the name on your card."},"empty":{"instruction_type":"error","instruction_message":"Please enter the name on your card."}},"privacy_policy":{"terms_title":"Terms and conditions","terms_body":null,"terms_show_text":"View Terms","terms_hide_text":"Hide Terms","initial":{"instruction_type":"normal","instruction_message":"I agree to the terms."},"unchecked":{"instruction_type":"error","instruction_message":"Please agree to the terms."},"checked":{"instruction_type":"success","instruction_message":"I agree to the terms."}},"email":{"placeholder_text":"Your email address","initial":{"instruction_type":"normal","instruction_message":"Enter your email address"},"success":{"instruction_type":"success","instruction_message":"Enter your email address"},"blank":{"instruction_type":"error","instruction_message":"Enter your email address"},"not_an_email_address":{"instruction_type":"error","instruction_message":"Make sure you have entered a valid email address"}},"note_with_tip":{"placeholder_text":"Your note here...","initial":{"instruction_type":"normal","instruction_message":"Attach a note to your tip (optional)"},"empty":{"instruction_type":"normal","instruction_message":"Attach a note to your tip (optional)"},"not_empty_initial":{"instruction_type":"normal","instruction_message":"Attach a note to your tip (optional)"},"saving":{"instruction_type":"normal","instruction_message":"Saving note..."},"success":{"instruction_type":"success","instruction_message":"Note successfully saved!"},"error":{"instruction_type":"error","instruction_message":"Unable to save note note at this time. Please try again."}},"email_for_login_code":{"placeholder_text":"Your email address","initial":{"instruction_type":"normal","instruction_message":"Enter your email to log in."},"success":{"instruction_type":"success","instruction_message":"Enter your email to log in."},"blank":{"instruction_type":"error","instruction_message":"Enter your email to log in."},"empty":{"instruction_type":"error","instruction_message":"Enter your email to log in."}},"login_code":{"initial":{"instruction_type":"normal","instruction_message":"Check your email and enter the login code."},"success":{"instruction_type":"success","instruction_message":"Check your email and enter the login code."},"blank":{"instruction_type":"error","instruction_message":"Check your email and enter the login code."},"empty":{"instruction_type":"error","instruction_message":"Check your email and enter the login code."}},"stripe_all_in_one":{"initial":{"instruction_type":"normal","instruction_message":"Enter your credit card details here."},"empty":{"instruction_type":"error","instruction_message":"Enter your credit card details here."},"success":{"instruction_type":"normal","instruction_message":"Enter your credit card details here."},"invalid_number":{"instruction_type":"error","instruction_message":"The card number is not a valid credit card number."},"invalid_expiry_month":{"instruction_type":"error","instruction_message":"The card's expiration month is invalid."},"invalid_expiry_year":{"instruction_type":"error","instruction_message":"The card's expiration year is invalid."},"invalid_cvc":{"instruction_type":"error","instruction_message":"The card's security code is invalid."},"incorrect_number":{"instruction_type":"error","instruction_message":"The card number is incorrect."},"incomplete_number":{"instruction_type":"error","instruction_message":"The card number is incomplete."},"incomplete_cvc":{"instruction_type":"error","instruction_message":"The card's security code is incomplete."},"incomplete_expiry":{"instruction_type":"error","instruction_message":"The card's expiration date is incomplete."},"incomplete_zip":{"instruction_type":"error","instruction_message":"The card's zip code is incomplete."},"expired_card":{"instruction_type":"error","instruction_message":"The card has expired."},"incorrect_cvc":{"instruction_type":"error","instruction_message":"The card's security code is incorrect."},"incorrect_zip":{"instruction_type":"error","instruction_message":"The card's zip code failed validation."},"invalid_expiry_year_past":{"instruction_type":"error","instruction_message":"The card's expiration year is in the past"},"card_declined":{"instruction_type":"error","instruction_message":"The card was declined."},"missing":{"instruction_type":"error","instruction_message":"There is no card on a customer that is being charged."},"processing_error":{"instruction_type":"error","instruction_message":"An error occurred while processing the card."},"invalid_request_error":{"instruction_type":"error","instruction_message":"Unable to process this payment, please try again or use alternative method."},"invalid_sofort_country":{"instruction_type":"error","instruction_message":"The billing country is not accepted by SOFORT. Please try another country."}}}},"fetched_oembed_html":false}
ManageBy parameter can be used to provide multiple owners during group creation. (New-UnifiedGroup)
Wow. I haven’t looked at that post since 2018. Lots of changes since then, so I have refreshed the text.