"She has sent her girlfriend two letters."
Translation:Hun har sendt sin kæreste to breve.
You use sin/sit/sine when it refers to the same subject of the sentence: She sent her friend a letter = hun sendte sin veninde et brev If the owner is different from the subject, or it hasn't been introduced in the first place, you use hendes: She met her (of another girl's) friend = hun mødte hendes veninde Her friend is old = hendes veninde er gammel
I find the example extremely confusing. I was under the impression that karæeste meant someone who is romantically involved, as in English that's what girlfriend normally means. The only place I've heard it used otherwise was by 1st generation English speakers, the majority of which were incidentally from the Danish community, which is what, along with the sentence above, gives me the very strong impression the danish equivalent karæeste can be used for both interchangeably, but if a native or really well versed Dansk speaker could verify that, we would be quite grateful, as it looks like no one has really confirmed it for certain that I could see. Mange tak for hjælpen!