Combine two Conferences together?

Can someone please point me at a solution. I have searched for hours to no avail. Please excuse me if this in not the correct place to ask this question. (admin has my permission to move it as needed)

I would like to be able to combine two existing conference rooms together and then separate them.

Example:

Conference Room 100
Users: A, B and C

Conference Room 200
Users: D, E and F

Hypothetically… I would pick up an unused extension ( say extension 4000) and dial “123456”. Conference rooms 100 & 200 would be connected and all users A, B, C, D, E & F would be able to hear each other.

Then I would hang up extension 4000 and the two conference rooms would separate and return to their original state without disconnecting the original users. (i.e. Conference Room 100 with Users: A, B and C…Conference Room 200 with Users: D, E and F)

I think this might be done by connecting extension 4000 to both conference rooms at the same time. This might allow extension 4000 to temporarily join the conference rooms into one virtual conference room.

I am using FreePBX 2.6.0 with Asterisk 1.4.21.2

Any help on this would be appreciated.