For purposes of Regulation AA the term “co-signer” means
“a natural person who assumes liability for the obligation of a consumer without receiving goods, services, or money in return for the obligation, or, in the case of an open-end credit obligation, without receiving the contractual right to obtain extensions of credit under the account.
The term includes any person whose signature is requested as a condition to granting credit to a consumer, or as a condition for forbearance on collection of a consumer’s obligation that is in default. The term does not include a spouse whose signature is required on a credit obligation to perfect a security interest pursuant to state law”
The mother does not appear to be a “co-signer” since she receives “goods, services, or money in return for the obligation.”