My son had j pouch when he was 9, after drastic UC struggles. They predict one week in the hospital, but my son had postop complications, and stayed 3 weeks. Doing great now tho. If the children are otherwise healthy, they can probably do the pouch with 2 surgeries, with them having a colostomy bag in between. While the bag is a bit of a hassle, it's better than UC, but you have to stay on it, keep it clean, keep it emptied, etc. My son was very sick after his bout with UC, so needed 3 surgeries.
If healthy and all goes well, one week in the hospital and one week at home, then think about easing back into a schedule, if everything goes by the book. However, with 2 of them, it will depend on how much help you have, and their own attitudes. I would plan for at least 3 weeks out, and in the summer, if possible. Some home schooling and/or home tutoring could help with the transition, if allowed.
He is a normal boy now, playing soccer and tennis and video games, teasing his sister, etc. Takes immodium and iron.
We were at Riley, with Dr. Rescorla. Billmire also did one of the followups, probably saved his life. They are GREAT at Riley.
Best of luck.