I've only got one, but I've seen two children two years apart work really really well in gifted families - built in best friend! Also, the drastic changes seem to occur, by my observation, when #2 starts crawling and grabbing #1's stuff. Untill then you can put #2 in a sling, and back-willing, keep going on as before!

Best Wishes,
Trinity

Coaching available, at SchoolSuccessSolutions.com