Actually some SAs that are linked to attributes -aerial-heading etc- don't consideer as a main skill, the attribute assigned to the own SA...

So, my suggestion is:
New Position = all Phys&ment attributes in white
SA= attack/defense, depending on main position or some criteria... skills, in white.

Double SA, atta/def in white.

Ofc we could suggest more options such a 2nd and a 3rd level -adding a +2 and +3 star to the affected attribute- for the SAs... and a etc.