Consists should able to be made and broken on the fly.
NCE does offer a method to apply when using a group of locos in a dedicated helper consist. They call it a "nesting consist". It uses both their "advanced consisting" (consist info stored in the decoder's CV19) and as they call it "old style consisting" (consist info stored in the base station) and build the helper consist as an old style (also known as universal?) The method is as follows:
Nesting consists: Say a heavy freight is approaching a long grade and helpers are needed. The train’s locomotives are an advanced consist. The two pushers are also consisted using an advanced consist.
The pusher consist is brought out of the siding at the base of the grade and put in place (coupled to the train).
An “old style” consist is now set up using the freight’s lead loco number and the pusher’s lead loco number.
You can now operate the entire train to the grade crest as one unit.
Upon reaching the cutoff siding at the crest,
the “old style” consist is killed and the pushers are selected (using the Helper's "Advanced consist") to move to the siding.
The freight consist continues (using the Lead loco Advanced consist)
on while the pushers drift back down the hill.
In step-by-step:
- NCE "Advanced Consist" the lead-loco set
- NCE "Advance Consist" the helper loco set
- then use "Old Style" consisting to link the Lead and Helper loco sets together as one "train"
When it comes time to "cut off the helpers",
simply delete the "Old-Style" (whole train) consist,
and drive the lead-loco and helper-loco (Advanced) consists off on their separate ways...
I tried not quite this once on the club layout with mid train helpers. It worked well, but I was using all Genesis 6 axle locos, but that of course, involved stopping the train to separate the 2 halves. If you have a situation where you have a dedicated helper set used as pushers, and have the front coupler locked in the open position so it can disengage easily, it might be possible to achieve the decoupling on the move, so long as the main train has clear track ahead, because both loco sets could still be responding to the advanced consist commands (I say, could) when the "Old Style" was killed (you think?) Then you could grab the helpers again and bring them to a halt. The instructions seem to imply this. I think there is too, a method in the NCE cab where you can toggle (scroll addresses and select) between advanced consists.