Legal Question in Real Estate Law in California

I'm not sure what you mean by "carry the loan." The term carry the loan is usually used in a situation in which the seller is paid a down payment, and finances the remaining balance of the purchase price with what is called a carry back. In that situation, the buyer makes payments on the remaining balance to the seller, rather than to a third party lender. This doesn't make any sense in the way that you have posted it.

Upon sale the current balance of the reverse mortgage loan is due and payable "in full", and WILL be paid off from sale proceeds, or the escrow WILL NOT close. That is non negotiable. As long as that is paid off upon close of escrow, you can make any financing arrangement you like with the buyer for the balance of the purchase/sale price.