I know several blades nestle into the bottom of the tray for the TS55 Systainer insert. Up to five I think, if you don't have connector bars there, and if you don't mind them touching. Probably four if you separate each with some shielding (e.g. milk jug plastic/coffee can lid).
For those who have TS75s, is there a blade "compartment" in the tray insert?
I've got 2 blades in my systainer for the ts75, one on each side of the insert that holds the saw, there are cutouts in it.

Dan.