If you tell Keldorn to go and be with his family during his personal quest in SoA, can you call him when you have that option to summon NPCs in ToB?

I've got a really powerful 3 person party in SoA right now, and I'm conisdering adding a low level Keldorn to this party to add some fun right now. But I'm also considering the idea of releasing him when I meet him and his family, and then adding him in ToB later.

Yes, you can call him.

Sure, Klorox...I do it all the time. I've actually never taken Keldorn away from his family in SoA, but I drag everyone and their mother to the pocket plane in ToB whether I'm going to use them or not, both for the cheesy 2000 XP and for the dialogue.

If you tell Keldorn to "just wait here", he tells you that he feels he'd serve better with you or at home with his family, but he'll do as you wish. Like he's got a choice. ;)