Can I control how many forms are submitted via subgroups selected thru a field?

I am not sure if I understand your query correctly. Do you mean to restrict the users to submit the form based on any field? If so, is there any specific number of each group? In this case, you may consider using one of the following widgets that might help achieving your requirement.

https://widgets.jotform.com/widget/appointment_slots

https://widgets.jotform.com/widget/gift_registry

https://widgets.jotform.com/widget/quantity_gift_registry

https://widgets.jotform.com/widget/ticket_purchases 

Please give it a try and let us know if you need any further assistance. We will be happy to help.