Fall from Dreams

You usually have to fiddle with the neckline of the TS3 mesh to fit the TS2 better - this is mostly for aesthetics really XD TS3 bodies just seem...meatier for some reason, compared to TS2, so if you don't mind that look, it's okay to skip that part.

As for merging vertices, yes - inside the sleeves, around the neckline and for bottoms around the waist. Make sure the TS2 mesh is the first one in the groups' list before using "Vertex Data Merge", since it merges the vertices to whichever mesh is top of the list (this is especially important for bottoms to line up with the waist).

And no worries :) Always glad to help and answer questions! I hope I answered yours well ^^;