I just got a Western Union money order from a person I sold a shirt to on an online selling and trading forum. I had requested a USPS money order, but she sent me a Western Union one, and for some reason the forum hasn't been working and I can't get into contact with her. So I decided to try to cash the money order but since I'm under 18 without a state ID (New York), my sister (18+) usually helps me cash my money orders into her bank account. But she said at the bank, the teller says my sister can't cash it for me. The thing is, she signed the back of the money order beforehand, and the back of the money order says "Should this item bear any unauthorized signature...". :( Is there any way I can still cash it? Say at a Western Union office, when both my sister and I are present? Please let me know, thanks in advance!