A purchaser is a person who is obligated to make payments under a prepaid tuition contract. Joint purchasers may enter into a single prepaid tuition contract if they are married on the date of application. Each person that is a purchaser under a prepaid tuition contract is jointly and severally liable for all payments and fees due under such contract. Unless otherwise provided in these rules, the purchaser shall execute all prepaid tuition contract changes, conversions, transfers, terminations and refund requests, and if there are joint purchasers for a single prepaid tuition contract, both purchasers must execute to effect such actions. Any requests to change the purchaser must be signed and notarized by the purchaser. A purchaser may designate in writing to the board a person with a right of survivorship in the event of the purchaser's death. However, until the rights under the contract pass to the designee, such designee has no right to direct decisions regarding contract changes, conversions, transfers or termination. Without limitation on the foregoing, the contract may be modified or terminated by, or refund disbursed to, the purchaser without the consent or authorization of a designee of survivorship rights pursuant to this paragraph.