HA while living with parents to save for downpayment

by Nel
(Georgia)

My husband and I are trying to sell our house to build a new one. We will probably end up living with his parents for six months (rent free) next year while the new house is finished. Any money we save will be used towards the downpayment for the new house.

Can we use the Fair Market Value of living in half of his parents' very large home for six months and our new house for six months? This number will probably be lower than our actual expenses since we are trying to scrape together a large down payment. Or do we request that our organization lower our housing allowance next year since we will be living rent-free for six months, even though we know we will be making a large down payment mid-year?

Suggestions are appreciated!