Hi Barb,
Sorry, the feature list for AR 9.0A has been decided, and a data entry template for adding a new customer is not on that list.
It's pretty easy to have a SmartFinder list that selects all customers with a blank report group for editing, or even a GridView View that is automatically updated when customers are added that highlights customers with "incorrect" groups.
While you are looking for report group as a required field, others would want the same for territory, or salesperson or credit limit or... See how these things snowball!?

Hopefully for next time.