It is; just do a reanimation and a transformation syndrome in the same step. Always worked for me.
Pls tell me how, i tried to make cultists before that were basically normal necromancers exept they could summon demons and abominations but i could never get the transformation part to work
Edit: Nvm, for some reason i never tried to simply add transformation in the same interaction and instead tried to make the reanimated corpse have vampire-like blood that would instantly cause it to give itself another interaction that was the transformation.