Downsizing - Buy 1st, then sell - Creative financing question

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I'm in the process of downsizing and, as I am not a real estate pro, I'm trying to learn all I can in order to make the right decisions.  I want to buy the downsized house first, then sell my old house.  My end goal is to be mortgage-free asap. Unfortunately, the proceeds from the sale of my old house would not completely pay off the new mortgage on the new house and leave me with about a 60-75K balance, so I figured I would put the proceeds towards a recast of the new mortgage to greatly reduce the montly payments.  I'm researching various lenders and one of them has recommended that instead of a recast, they could break up the total loan amount initially needed to buy the new house into two loans. Once I sold my current home, they would pay off the 2nd loan, eliminating that loan amount & payment, leaving me with the 1st and only mortgage loan. They say I would not have to go thru the recast option, which has to be reviewed & approved.  I've never heard of the split into two loans option and thought I'd reach out to the experts here at Bigger Pockets to see if you thought this option is a good idea or not.  Please share your thoughts.  Thanks!