I have Adobe connect 100 seat manager. The next step up is the 500 seat. Is it possible to buy a 2nd 100 seat manager and merge the 200 to give me 200 total seats for our chat room?
No, Named Host licenses cannot be combined.
You can get a Named Virtual Classroom Manager license (that one is truly a mouthful) and it has a seating capacity of 200. The Virtual Classrooms reside in the Training module of Connect but are functionally the same as a Meeting Room.
That would be the most reasonable option to get a seating capacity of 200 for a room.