My nephew was married a couple years ago. The two young ladies who were flower girls had adorable purple/white/yellow floral dresses that were off the rack from a local clothing store.
The bride's cousin wanted her two girls in the wedding. She found out what the flower girls were wearing, went to the store and bought the same dresses for her girls, showed up at the wedding with the girls in these dresses, then tried to force the bride to put them in the wedding. My brother, the father of the groom and someone who doesn't put up with bad behavior, towered his 6' 6" frame over them and told them to please have a seat in the sanctuary. They slinked away without another word.
I showed up in a periwinkle dress. Fortunately it was closer to a blue shade so I didn't match the wedding party. But then, I wasn't trying to be in the wedding party.