The property may only be redeemed by the judgment debtor or the judgment debtor’s successor in interest. For this purpose the purchaser at the sale is not a successor in interest. (CCP 729.020)
If there is more than one judgment debtor, a successor in interest of any of the judgment debtors is entitled to redeem the whole property, as property that is sold as a whole may only be redeemed as a whole. (Emerson v. Yosemite Gold Mining, 149 C 50)