Uneven wedding party, so only some standing?

My fiance wants his best friend to be his best man but doesn't want any other groomsmen. I am choosing my best friend as my MOH but also want my sisters to be bridesmaids. However, to keep it even during the ceremony I'll just have MOH stand. MOH will be in sage green (any style dress), and I've asked my sisters to wear the other two wedding colors (one in burgundy, one in blush, also any style they prefer). I want this for pictures and also because they will be with me during the day and helping me get ready (my older sister will be doing my makeup, my younger sister will be doing my hair, they'll be helping me make sure things are ready to go, etc.). One of my sisters is insisting this isn't traditional and shouldn't be done. Am I way off the mark here?