Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Dear Thomas Mosley,
Good day! Thank you for posting your query in our community.
Per your description, may I confirm whether you want to have an existing group(required) option when users create a new plan?
If yes, generally, when you create a plan, you can add to an existing Microsoft 365 Group or skip the link if you want to create a new group when you create this plan. If you don't add the plan to an existing group, creating a plan also creates a new Microsoft 365 Group.
Given this situation, I do understand the inconvenience and apologize for it. We recommend that you submit requirement for this feature in this Planner feedback portal and Microsoft is committed to continuously improving your experience with our products.
If my understanding is wrong, please feel free to post back.
Sincerely,
Jazlyn | Microsoft Community Moderator