(((Dorton))) - I think you will do just fine. I also think taking your nieces is an excellent idea!! There's nothing like having little kids around, to take the focus off of anyone but THEM. I would make sure I planned some "kid friendly" things for the girls..just to remind him that this is his family thing.
When I first got clean, I hadn't seen my little niece and nephew in almost 2 years. My nephew was only 3 and didn't even know me, but my niece ran up and jumped in my arms. That is one of the things that made me want to stay clean even more...I'd missed them, and I realized that if I didn't STAY clean, I wouldn't have them in my lives, because I was not allowed around them if I was using.
I know you're nervous, but I hope it all turns out well.
Hugs and prayers!
Amy