Spin Off to Processional Order

Heres my question -- I DO NOT want the Groom and groomsmen to walk down the aisle. They're going to be waiting at the altar when the processional starts. My grandparents are all still living and married, but FH has one grandma who is widowed. FMIL says that FH's brother (who is the Best Man) should Usher her to her seat. BUT if he's going to be up at the altar, how can he do that? should he do that?
Same goes for my mom -- she'll be walking alone since my dad is walking me down the aisle. My brother (who is also in the BP) will be up at the altar already. Should I have him walk her anyway? Or should she walk alone?

Any advice would be helpful! Thanks ladies!

I think it would be nice to have them walked down the aisle, then maybe the GM can join the others already at the alter. JMO

I agree with the above, have them walk with them and then just join the rest of the BP

P.S. I think I might steal your idea for having the GM waiting