@James Bond i would recommend you use Moneygram instead of WU. You should be able to send to your mother in law a payment for free for the first payment. If you sign up you can send in as much as you want I believe. Just transfer to her Argentine account or if she has Mercado Pago account that should work. I just send into my normal bank account. Rate is always better than WU and fees are free for first one. It comes through quickly so might want to try that instead of WU. I also noticed they keep increasing their fees. I don't understand their business model as maybe it is just tourists. Most locals don't like using them now because of high fees. Tourists are stuck using them. Works well but fees are high.