do you know about the halachos of marriage
like kiddushin and nisuin
kiddushin aka eirusin is the first part, which functions halachically as engagement, except its more binding than the kinds of engagements we have nowadays because although the couple doesnt live under one roof, she is considered an "eishes ish," i.e. someone's wife and all the laws that apply to how one must interact with a woman on the basis of her being married, i.e. that she's forbidden to anyone else, apply in the old days they used to to kiddushin/eirusin at a given time, and then wait a year or so for the girls family to gather a dowry and the husband to get a house and stuff then a while later they'd do the second half, nisuin, and then theyre fully married and move in together we stopped doing that around the time of all the eastern european pogroms because sometimes if people lived in different cities, the man would get killed or something but no one would ever know for sure that he was dead so the girl could never remarry. This is called an agunah.
Anyway so theres an old out of practice custom called "kiddushei kitana" which literally means betrothal of a minor
In generations past, a father was allowed to betrothe his daughter with kiddushin before the age of 12.5, to ensure that if anything happened to her she'd be taken care of and have a husband.
My friend was involved in a case of kiddushei kitana where a guy didn't want to give his wife a get (i.e. the wife was an agunah) and one of the things he used to blackmail her was he told her that he did this to their daughter but wouldnt tell them who he betrothed her to, i.e. the 11 year old daughter was an agunah as well
My friend died in the middle and i never followed what happened in the end.
Anyway the point of my story: I just saw on onlysimchas that the girl got engaged. So i guess everything worked out.