Creating multiple records based on other entries

Hi! I have an interesting problem I’m trying to solve for.

I have users who belong to groups and each group has a quarterly fee (can change).

When the group owner creates a fee, I need to create a balance for each of the users in the group based on their percentage ownership. They’ll need to be able to pay the fee, then be marked as paid.

My first thought was that the group owner could create the transaction and I could use automations to increase a balance tied to each user, but I couldn’t figure that part out.

Any ideas? Thanks in advance.