A small clarification between terms, to the best of my knowledge if you are a 100% foreigner you cannot get a loan to get purchase property from a Chilean bank unless you have established ties in the community (such as a permanent job and a resident visa), at that point and depending upon the bank rules you can apply for a loan. On certain instances you may need an "aval" which in the States will translate as a cosigner and who will be responsible if you default on the loan.
A Mandatario Judicial on the other hand is not an aval, those are two separate things, but presumably can bee the same person. The Mandatario has no financial obligations to the debt but is the person that represents the principal on the loan if that person is consider a foreigner in the eyes of the bank. I'm Chilean by birth but live in the States and have some property in Chile, for my loan I have to get a Mandatario who will go and talk to the bank if they need to chat with me and I'm not available.
J.Ro.
Your situation is similar to mine, and you really don't need to give power of attorney's to the parents. Since you wife is from Chile she is entitled to apply for a loan from Banco Estado, check this page
http://www.bancoestado.cl/45BCFD49F3A44CA58CD433CEEEE708C1/5B93749A11BB4392B051BDDF716CE806/5B93749A11BB4392B051BDDF716CE806.aspYou can PM me if you want and go into more details about this.
Hugh