andrew and sam get engaged at the beginning, which is right after the first movie by maybe... 2 months. they arent at all worried abut their short time knowing each other, although andy's dad is making an issue of and he thinks andrew is rushing into it simply trying to mask his "guilt" and pain of losing mom with this new "infatuation". thing is, andy is quite happy with moms passing, because he knows she is out of her misery. he still feels horrible about hat happened, but he has a peace about it.

sam insists on knowing andy's dad, and basically laughs off all of his psychobabble nonsense with her usual charm and it... and essentially charm him the way she did andy, dad likes her, and accepts her, though still is unable to accept his sons "irrational behavior".

that would form the core of the movie, a love triangle of course between dad, andy, and sam. (obviously, not a romantic one between sam and dad) dad opens up to sam, and perhaps we learn a few things about him that make him seem more likeable, though his relationship with andrew will remain strained.

of course, we get more of mark in this one as well.
marks mom actually makes like $20,000 off her first real estate deal and gets a bunch of new furniture, including a new bed... whom she eagerly invites sir knight over to break it in.