Yes this is possible. I have a song that has 2 tempo changes, using this "at120&a1t60&a" plays it all like a single note. This song has 9 tracks and tempo changes are a pain. You just have to put the tempo change before the tie.
So, as most of the composers from Mabinogi may be aware of, a tempo change only has to be noted in 1 out of all 3 tracks, and all tracks will apply it. This allows us to insert tempo changes during ties as well, for example if I had c+8&c+8 that starts with t60, but speeds up after the first eight note into t90, I can do this by telling another track at the exact moment when the first note ends to switch to t90, and it will still apply to all tracks. This creates a more dynamic performance.
I noticed in MS2, that tempo changes have to be noted in every track, MS2MML will not look at tempo changes from other tracks for each track within the same score. Thus my question, is it possible to create a tempo change within a tie on the same track?
I tried t60c+8&t90c+8, however this breaks the tie, and 3mle plays both notes seperately. If anyone has insight into this, I'd greatly appreciate the input.