It rarely hurts to get a child evaluated. If they have only minor issues, you will find the issues much easier to address when they are young. Minor speech problems, for example, are easier to change at 3 than at 5.

My middle son was evaluated at age 4, we didn't notice problems with my oldest until he was 8 so he was evaluated 2 years after my middle son. WE have not had our youngest son evaluated because he shows no signs. I wouldn't evaluate until you have concerns.

I would not get the other child evaluated unless you have reason to do so. We had our children evaluated at 3 and 2 but we knew we had something going on with both. Our son was first at 3 and while they were at our home they suggested we do the same for our daughter who was 2. They suspected she was more affected and she was, my son is HFA and my daughter is nonverbal at 8 still.

Why would you get them evaluated unless there are concerns?