I will add a few things that I didn't see (though I might have missed)
1. I always make an itinerary out for each day of the trip. It's not all that detailed. It just states what park is planned for the day, the time of any meal reservations, the time of the nighttime shows, or the mid day parades, park hours, etc. Everything else is wide open and even things listed aren't necessary. Each night after coming back we wind down and look at the plans. Every one has an idea of what they want to do.
2. Even if we spent the day apart we would dine together most meals. We get the TiW card. During our nightly wind down we also went over receipts and noted in a small tablet the cost of their food. At the end of the week they wrote me a check. I know this isn't a good idea with some people, but if I don't feel comfortable enough with them to do that then they aren't vacationing with us!
3. I went a long stretch of not going to Disney when I got out into the world on my own. My husband and I could not afford it. I stayed at home with the kids for many years before going back to school. The first trip with our kids, we got the Birnbaum's Kids book. It described the rides and helped the kids decide what rides they wanted to definitely ride ahead of time, what they might ride, and what they wouldn't ride. We used this to make a list. Each family member picked a couple rides they wanted to ride. Once those were done anything extra was a bonus. This allowed us to relax and not think we had to do it all. This might be helpful for the family you are taking. My kids are taking friends next summer and I plan to gift books to the friends for Christmas, so they can help with planning.
4. If you decide not to do BLT, I would consider AKV Kidani Village instead of SSR. The points will be cheaper than BLT. The pool is fantastic for those ages, and so are the animals!! Also the 2 bedrooms would have the 3 bathrooms (same as BLT). That will help in the mornings! We decided to do AKV Savannah view instead of BLT in June because it saves about 43 points and we can get an extra night.
Hope you have a great trip!!!