Mhalir seizes tight control of Carissa's body, with a mental note of apology, and they cross.
It goes smoothly enough; it's maybe interesting for Carissa even though Mhalir finds it quite tedious. His staff are worried, in the usual way they are when something big and overwhelming and complicated is happening. (Which occurs kind of a lot, actually.) He goes through all the usual steps of reassuring them that he has a plan and that being involved is worthwhile in expectation and there are a lot of possible upsides here.
It takes some convincing that Leareth is definitely another of him/Aroden/Ma'ar, but less than the first time this came up. They are, eventually, amenable to following Leareth's Void-ship back and hanging around nearish the other Golarion.
Mhalir does a lot of reassuring them that he's definitely considering the Yeerks' interests in whatever treaty they eventually make with Leareth'a Cheliax or other powers in his Golarion; it's just that for now infosec comes first. (In actual fact he's barely thought about the political formalities side of things, but he's surprisingly good at sounding like he's on top of it anyway.)