My older DD4 likes to take things over too. I have a 2.5 year old also and it is tough to find things that are at the right level for both of them and that she won't try to dominate. Lately I just put my foot down and say that the older DD4 cannot answer certain questions and try to find something to do if the younger DD and I are doing something together. I try to find little moments alone with the younger child. Something as simple as taking her grocery shopping with me and having the older DD stay home with her dad. My girls are less than two years apart but that is a world of difference in some areas. Once I figure out the formula, I will let you know.