[andrewas]

The normal way to keep Yoshi after brynnlaw is to leave him in the CC and talk to him and take him into the party before he dies. Not easy, you should haste yourself and make sure hes near the door before you try it.

Hell still die, but if hes in your party you can resurrect him.

As for ToB, there is no reason for any problems, but he will lack the dialogues and such that make an NPC interesting. For that reason Im not going to do it.