WTW for that means someone who has come into your care

You would use it to describe someone you are caring for in a more permanent sense… an orphan you adopted or an animal. I don’t believe you would use it to describe caring for someone who is temporarily sick or babysitting. It may be a slightly older word, early 20th late 19th century? In a sentence would be something like “My sister died, so her daughter is now my…” I’m positive this word exists and I can’t think of anything close enough to use a thesaurus. My mind just wants me to use “boon” which is not what I mean at all. Thank you!