Slate the tracks so you can easily align them.
What does "slate" mean exactly in Reaper? Is there a specific slate function in it or is it a process that can be referred to as "slating?" I do have the 8 tracks grouped (so changes to one affect them all) if that's what you mean. The difficulty might lie in getting the next 8 tracks to align with the first 8 tracks. I also have all the clocks set to ADAT so that should help with aligment.