Dasha is 22, we got her at 15, by accident. We call her our adopted daughter, but we never legally adopted her because she has an actual mother. She was a foreign exchange student we 'rescued' from a school where I helped coach, brought to that school under dubious promises. Long story, it has been discussed here previously. We ended up getting power of attorney, she has alternately lived with us, traveled with us, lived with our natural daughter, vacationed with us, comes 'home' for holidays, etc etc etc. She clearly has become family. Took her to college visits, met with college recruiters, moved her into/out of her dorm and then apartment many times, have been coast to coast with her (multiple times) and cried tears of happiness when she graduated from college. Road tripped with her to her new job at Apple Computer in California to get her moved in there and are in daily contact with her to this day.
All I can tell you, as an accidental foreign exchange parent is that if you get one that fits into your family it can be a total blessing.
She will come home for Easter weekend in April. We hoped to get there in March but my sister-in-laws surgery is altering that plan. Maybe we'll get back to California to visit here in May/June? We literally communicate every day. Usually text messages. Sometimes photos. Sometimes FaceTime.