re: Resawing with TS

+1 on planing both sides. I was just working on a piece of 4/4 Purple Heart that must be case hardened. I resawed it in three pieces for the bottom and another piece without first thickness planing the full board. The two outer pieces cupped so badly they were unusable while the center piece was fine. I planed another piece of the board on both sides before the resaw process and had no problem with them.

As suggested, plane, resaw and plane to NEAR final thickness then let them relax while stickered up for a few days before planing to final thickness. Any cupping should be slight and one side should be flattened (in any of myriad ways) before running it through the thickness planer.