Junior Bridesmaids

Considering asking my 2 soon-to-be nieces to be junior bridesmaids - I believe they will be 10 and 12 at the time of the wedding.

Current plan: to have them join us in the bridal suite room of the chapel after the BM and I have gotten ready off site (chapel does not allow alcohol so we’re getting ready off site), maybe 30 minutes before the ceremony. I’d ask their mom to do their hair and any makeup beforehand and then they can get in their dresses (similar to the older BM dresses) at the chapel. Or they can get to the chapel before me and fully get ready at there - I don’t particularly care. Just want my inner group when I’m getting ready as I know I’ll be very nervous.

Then I’d have them walk down the aisle either together or one at a time, before other BMs, and then sit in a front/second pew with their parents. My mom suggested having them light candles on the stage steps before sitting but I can’t have real flames and don’t know my decor plan, so haven’t figured that idea out yet.
I know typically Junior BMs stand by the BMs for the ceremony. They are old enough to do so but I do not think they’d actually enjoy it in the moment and honestly the youngest is very squirmy and the oldest has intense resting bored face lolThey are sweet girls and we have a good relationship. I know they’d love to be involved in the wedding somehow but I don’t want them to be flower girls. It would also be better for mine & FH’s relationship with their parents if the girls were involved.
Trying to figure out the best way to plan this and also how to ask them and their parents in a way that’s exciting, but doesn’t make the parents upset that the girls won’t be standing for the ceremony. My future SIL told me not to worry about it and just make them Junior BMs and tell them how it’s going to work and to not care if their parents are bothered that the girls won’t be standing up there. Again I think the girls will just be excited to be involved and wear the BM dress and will not care too much about not standing.