MEBA isn’t connected to MMP so not necessarily. And I can’t image AMO would be able to fill all the new engineering jobs on their own. There are a ton of engineer openings on their online open board. I believe the passthrough that AMO and MEBA have is only one trip passthrough, so it wouldn’t work really for APL because you’d need permanent engineers especially CE and 1AE.
If APL is truly going to bring in all those ships and ditch MMP, it would have to be AMO deck and MEBA engine. MEBA is the only union with that could come close to filling all those engine jobs.