Since to open a PMS consent of all partners are required, the same can not be transferred by a sole partner in favour of a non partner.
So even if your father make such gift deed, the same would be in operative.
As PMS transfer by a sole partner without written consent of other partners is non effective the question of tax liability does not arise either.
The POA by other partners in favour of your father will not help as this transfer is something which is not usual act done by a partner in carrying out of usual business of the firm and hence such transfer on the basis of POA would be unauthorised act of your father and would not bind the other partners as well.