Wedding shoes

So I have been going back and forth with my bridesmaids for the past 2 days now saying I want everyone to wear flats who is in the wedding party. I am only 5'1 and they are all taller than me by at least an inch. I don't want to wear heels and I don't want any of them to wear heels. it is a garden wedding it seems unnecessary and I feel them wearing heels will skew the pictures. some of them have agreed but one keeps going back saying I want to wear heels. do I tell her to wear heels but don't walk down the aisle because it's really frustrating me that this is one simple request