Poster, bridesmaids are not usually little girls. It refers to friends of kallah marching down to chuppa. Definitely not tznius to have teenage or adult females parading in front of a mixed audience all dressed up and made up to the nth degree. (They will assure you the excessive cosmetic application is for the photographer.) Especially inappropriate at a chupa which is a very holy slice of time. However, very common in some circles. I have seen many times; do not feel qualified to pass judgement when I observe since, as I mentioned, some kallahs seem to like it. It is an adopted “minhag” from non-Jewish weddings.
Mazel Tov Seahorse! You should definitely discuss with someone knowledgeable that you feel comfortable with.