ABBA - Autograph Problem

[Emilio558]

I tried to submit an autograph request to the ABBA group on the addresses given to me but I forgot to include an SASE, I live in the United States and my mom suggested I should wait till the package arrives in Sweden and I make the call the phone number with the address, usually they have agents if there’s a way to pay for the return postage once signed, she doesn’t even know if it works and we don’t speak Swedish. What should I do?