Hey travelers!

I would really appreciate if someone could bring some light into this matter:

I am about to buy a camper in Santiago de Chile. The current owners have been travelling with the car for a year, without ever owning it. They used a „Poder de Notaria“ from the owner of the car. The car is registered in Mexico. The owner now lives in Argentina and agreed to come to Santiago to issue a new „Poder de Notaria“ for me. (The car is registered in Mexico. Will be sold with a Power of Attorney (Poder de Notaria) and a compra-venta.)  As it seems to me, I shall thus be fine going back and forth in South America – am I right? However, the original owner will presumably not want to come back every year the car is passed on. So this is where I will be stuck I suppose. Will I be able to pass on the car after my trip is done with? What legal terms do I need to be aware of? As I said, I really appreciate all the information I can get,

cheers,
Stefan