A transfer may be made only for one minor, and up to two persons may be joint custodians. All custodial property held under this chapter by the same custodian or joint custodians for the benefit of the same minor constitutes a single custodianship. Unless otherwise specified in any document creating the custodial property, each joint custodian shall have full power and authority to act alone with respect to the custodial property. If either joint custodian resigns, dies, becomes incapacitated, or is removed, then the remaining joint custodian shall become sole custodian.