Welcome! This forum has a treasure trove of great info – Scouters helping Scouters! Just a heads up, though - all content, information, and opinions shared on this forum are those of the author, not the BSA.
(and I believe the ‘combining registrations’ aspect is what got me stuck in the first place - any specifics you could provide that I can pass to them would be great)
Your Troop Committee Chair and COR registrations are under one BSA member number, but your Merit Badge Counselor registration is under a different number. Because they are both in the same council, I would recommend that your council Registrar combine them all under a single BSA number.