Only if it manifests as True Form...

Besides, if it was standing next to me in its own body, it could still fry you just fine.
...And I could be possessed by a temporary Fire Spirit giving me the same ability to fry you at the same time.
If the Ally is me, and I am the Ally, at least number of actions are limited to one of us acting at a time. The line is blurred though, since "we" can use any and all of our abilities, and any of our skills. - Major drawback is Dual Natured, but it gives other advantages.
So my question is, would you allow one parts skill to aid the other parts power? - Mmm.. Writing this I'm thinking up too many ways that would go broken very fast. Each power should use relevant skill from same person.
Anyhow, I will be using this thread to receive input from you all.
My vision is a quabbalistic witch type. High quality mechanical pets for possessions, magic symbols tattoed and burned into her body with the Ally spirits formula, and of course it is taken with the Familiar Ordeal and after Channelling is already taken.
I'd take the powers, Movement, Conceal, Guard, Accident, Influence and Elemental Attack for a classic pop-culture sorceress using charm, curses and blasting power. - Loosely inspired by reading too many comic books.
The spirit would be bringing physical stats, armor and Aid Sorcery to the table, as well as Assensing, Dodge and Unarmed Combat.
The character would focus on summoning and spellcasting.
A question though, the spirit when Inhabiting, would lose Astral Form, yes? - And how about the character, would you be able to leave for awhile and return later?
And the Initiative Passes, spirit brings 2P, base form using a spell could raise to 4P, but how about Adept Power, Increased Reflexes in a situation where I have Channelling? - I can use all my other skills and abilities, wouldn't this power remain active too? - Basically that question goes for all Adept powers.
Those two issues and the interpretation of them will likely decide whether I go Mystical Adept or Mage.