This is an outgrowth of the Patriarchy movement, I've brought this issue up before, but it seems these purity balls are growing in popularity. A young girl should be following God's will, not following the edicts of her father in pledging her purity to him which crosses so many false boundaries it's not funny. The psychologists may refer to it as "covert incest" but something is clearly wrong with those making legalistic ceremonies out of virginity for girls. What if a girl's father is not a Christian or is even abusive or horrors beyond horrors sexually abusive? This reminds me of Catholicism where they have the novices wanting to be nuns dress in white wedding gowns and have them "marry" "jesus" with their heads shaved making vows of virginity [chastity] and often poverty.
'You are married to the Lord and your daddy is your boyfriend':
"Fathers taking part are expected to sign a ‘purity covenant’ in which they, as ‘High Priest of their home and family’ pledge ‘before God to cover my daughter as her authority and protection in the area of purity’The daughters silently commit to live pure lives before God through the symbol of laying down a white rose at the cross, before engaging in a wedding-type dance with their father."
False theology predominates here as well as legalism. A girl should stay pure to please the Lord not to please her human father.