Article 394 of Civil Code

If payment is made by a person other than the debtor, the payer shall be subrogated to the creditor who received satisfaction of his right in the following cases: (a) If the payer is liable for the debt together with the debtor or is obliged to pay it on his behalf. (b) If the payer is a creditor and pays another creditor having priority over him by virtue of real security, even if the payer has no security. (c) If the payer has acquired ownership of a thing and paid the debt to a creditor whose right is secured by that thing. (d) If a special provision grants the payer the right of subrogation.