What a marvelous man you have, that his STEP-son wants
to keep in touch with him.
Since you know you will say yes to your husband's request,
do it gracefully, and dear hubby will have that love in his mind
for the rest of his life.
And, you just may be surprised at how nice the kid may be,
of course he's old enough to know it was you whom he
has to really thank for letting him back into STEP dad's life.
Go for it, he's not moving in permanently, and, like Flylady
says="You can do anything for fifteen minutes" so take this
a little further="You can stand any visitor for three days or so".
Try it, you might make a difference in this kid's life. Maybe he
does not have a good mother figure in his life right now. We
do not know what is going on in other's lives.