How do you structure a growing Success team?

Hi all!

I'd like some insight into Success team structures. We've seen a lot of changes at my company recently, and I want to make sure we're set up well.

I'm currently the Director of Success at EverCheck with a team of 5 mid-market and SMB CSMs as well as 3 enterprise CSMs. We recently joined with our sister company, CE Broker, and today we're announcing an acquisition, both of which have their own Success teams coming under me now.

What's a healthy structure in terms of supervisors/leads/managers or other supporting staff on Success teams of 15+ people?