What age is too young for junior BM?

My FH has a niece that is i think 6 years old now. So she'll be about 7 or 8 when we get married. I was gonna have her as one of the FG's along w/ his other niece who will be about 5 or 6 when we get married.

My question is do you think the older niece will be too old to be a FG or too young to be a junior BM?

I dont know what to do.

I had my 7 yr old cousin be my Jr. BM....she had the same dress as my BMs but little.


Then my 5 yr old cousin was my FG.

When I was 9 I was a jr BM for my uncle's wedding. Only reason being is bc his wife's brother was the same age as me.

I'm actually having their 2 daughters in my BP. The 12 year old as a BM, and her 8 yr old sister as a jr BM. We don't have any younger children in either side of our family to have as our FG or RB, so we're opting that part out.