Can we have tempo/signature track markers locked in time?

I started scoring some film projects the last year or so and I have never really figured out a good workflow for locking MIDI to timecode while still having the parts staying in sync with the tempo track.

Is there a way, or could we get a way, to lock select tempo and signature markers to timecode etc. so that only parts previous to that point get affected by tempo track and signature changes? That way I could lock the start of MIDI parts to cues and still change the tempo of previous cues without messing up the sync of my whole project.

Currently, I use MIDI/marker tracks with the timecode in the description so I can get the various parts aligned to their intended timecode, but it isn’t really optimal.

Or if anyone’s got a sweet solution for this problem, please enlighten me.