we were talking about this at team training camp recently - we ended up with this:

If at any point the break passes when they are a lap ahead of you (because they went forward from the pack and you went behind) than you have been lapped and you are done (such as pulling and then rotating back, you'd be done.)
Technically, if you stay in front of them and they don't pass you at any point (so you are basically pulling them) than you haven't bee lapped and can keep riding... but I have yet to be in a race where the refs don't signal to the "soon to be lapped" riders at least a short ways before the break gets there that they have been pulled.
This was the team consensus (because someone joked about doing the same thing... and was jovially told to GTFO)

Also, IIRC, the rule book states that you may not work with any riders who are not in the same Cat/Wave/lap as you... check your rulebook, but I'm pretty sure that is what it says. Thus, since the break isn't on the same lap as you, no you may not ride with them.

now - let's have someone who knows what they are talking about give us the real answer - cdr, RX, others?