PF: Is it possible for a GF candidate to spend a part of the outgoing phase in one third country and another part in another third country provided they will be hosted by different offices of the same institution?

It seems to be possible as long as the associated partner for the outgoing phase is a single independent legal entity established in a non-associated Third Country. Please note that the hosting arrangements need to be explicitly explained in both the application and in the letter of commitment to be submitted by the associated partner confirming their role and participation in the proposal.