K.,
I'm in a similar boat. My 3 1/2 year old daughter is still wearing pull-ups at night. She does fine at nap time and has actually been great on the potty for quite a while. She never "poops" anywhere but the potty. I think (as previous responses) it may be just laziness in the morning since she has the security of the pull-up.
At her three year check up I talked with her pediatrician, who seemed unconcerned about the nighttime issue, even suggesting that a three year old's bladder wasn't ready for nighttime. I've seen varying opinions, but quite honestly feel I missed an opportunity during the initial potty training, so....am considering going cold turkey, as in previous advice. I've been having the discussions with her, so if you need someone to bounce off of while you're going through this let me know:-)
I appreciate the previous advice on double sheets and pads. That certainly will shorten the middle of the night wet bed routine! If, as someone else suggested, it only takes a week, I can certainly get though that. I have a friend who bribed hers with one M&M for each night she stayed dry and that worked (over the sticker chart) like a charm.
You have some added issues with adopted children, meaning he may have some issues that overshadow the potty training difficulties. I don't know how long they've been with you, but I imagine working to gain some semblance of "normal" has to be a good thing. Good luck to you!