slide multiple regions in a track leftward to fill all gaps between each?

Long time listener, first time caller. Thank you for all the questions and answers I've learned from! I finally have an opportunity for one of my own, as I can't find an answer.

I recently decided that since Logic's transport tempo indicator is fixed to quarter note beats, and can't be changed to dotted quarters for compound time signatures like 12/8, I'd rather just leave compound time songs as 4/4 with triplets. I'm not working in score, and I can easily change grid subdivisions to 3-based if needed, so it seems like the better way. Then I can see the true tempo of a song, regardless of whether it's in simple or compound time. (And, after all, 12/8 is just a convoluted way of indicating 4/4, with three subdivisions per quarter note instead of two.)

(I came to this conclusion after reading this: viewtopic.php?t=53074)

My question is whether there's any easy way to retroactively convert existing songs (or, at least, pure MIDI songs) I've made with a 12/8 time signature in Logic. It seems to me the steps would be:

- change the time signature from 12/8 to 4/4 (this will cause the grid measures to change, so the regions will go off-grid)

- reduce the tempo by 33.3333% (thus setting the real BPM, since the tempo indication in the transport when at 12/8 was 50% inflated)

- time stretch all regions to reduce by one-third (so now region lengths correspond to the new grid measure length, and notes play correctly at the revised tempo)

- (this is the question; is it possible?) slide all the regions leftwards to close the gaps formed by the time stretching (making regions start at the same measures they did before, when the song was in 12/8)

The closest I've come is to join an entire track into a single region, and time stretch it to end at the identical measure as it did previously. But then I'd have to split it all back up manually. And if I have to do that, I might as well just note the position of each region when in 12/8, and then manually reposition once in 4/4. And if I have to do that, then I'd just say it's not worth it, and leave alone what's already done in 12/8, and make a mental note that the tempo shown in transport should be reduced by one-third.

Thanks for any suggestions!

Thank you! Very helpful. Didn't know about that. It does have the undesirable effect of closing up not just the newly created space following the time stretch, but also the original intended space. But there are a few ways I found to work around that, the best of which is just creating differently colored (so I can easily remove them later) empty regions to fill any gaps between regions, before I do anything.

But, from another post here, I found a better solution: SMPTE locking the regions and automation events before making the tempo change does exactly what I want -- no time stretching needed following the tempo change. But that yields a new question, which I'll ask in a separate thread since it's really a separate question. Thanks again for answering this one.