We had some gifts that several families went in on together. For those, we obviously wrote a separate TY note to each family.
But we had one gift, a GC, that a dating couple got together. They don't TECHNICALLY live together, but she is essentially staying with him for the summer. Can I just write them one TY and send to his address, where she is pretty much staying, or should I stick with one for each?

Everything the light touches is my kingdom.