@Scott Leerssen
Thank you for your post!
I wasn't able to find any information on creating a custom RBAC role with the least amount of permissions to create a new subscription within an Enterprise Agreement. Additionally, based off our Azure RBAC and Azure AD RBAC built-in roles documentation, I didn't find any reference to the Account Owner role that is required in order to make a new EA subscription. Since I'm not too familiar with the EA portal, I've added the azure-cost-management tag to this thread so their community can take a look into this issue as well.
Additional Link:
Where do I go to create a subscription?
Managing Azure Enterprise Agreement roles
If you have any other questions, please let me know.
Thank you for your time and patience throughout this issue.
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