Ooh I do like all this etymology.
I am enjoying nosing through that english - old norse dictionary. It's so interesting which words have many versions, which have double meanings. I note that there is a word for the verb foster (fóstra), and the same word means foster-mother (rather depersonalising). Then foster son (fóstra), foster father (also fóstra), and foster brother (fóstbróðir). No word for foster sister or daughter though. I can't help but wonder if there's a reason those haven't been recorded.
I'd very like to see what the kvenna on Kvennváðir&Fegrð think of that hǫnd-belgr**.
*women, wives
**women's clothing and beauty