Combining midi across separately/similar beat mapped tracks

Hello,  I'm hoping there is an engineer/rocket scientist here that can help me.  

 I need a workflow from someone who has cracked this riddle. I'd pay for it actually.

I have a stereo mix that has many tempo and meter changes.  I beat mapped it. I then recorded a midi piano part to it.

I opened a copy of the song a few months later forgetting that I beat mapped the original one.

I beat mapped again (slight timing variations but exact same overall tempo within a beat) and I recorded some more orchestration in midi.

They were both a lot of work - not easily re-doable for me.  They also both start at different bars.  

I'd like to paste or import the midi track from one project into the other.  I enabled beat mapping and protect midi.

I tried gluing and locking the region followed by an import.  They were out of synch so I tried again with cut and paste (which seem to preserve the timing to some extent) as opposed to dragging the file (which moved the region but not the midi.)

Is there an 'export tempo to region' command for midi?  Can I use the score editor to help me somehow?  Are scene markers or region start markers helpful?

Protecting midi on import is useless because I have to shift the region and the midi falls out of synch.  Both projects are 48k.  I've tried to use tempo alternatives.

I also have difficulty figuring out how to shift the song start properly. It seems like i'm limited to  about 8 bars back and 2 forward.

Any workflow would be greatly appreciated and can be used to combine a variety of different work I've accumulated.  I often think I have the solution but seem to be thwarted at every turn.  Thanks