Remortgage

Lubylue

In 2006 my brother got my mother to remortgage her house for £120,000. The mortgage is in her name but my brother makes the interest only repayments. Can this be considered a loan? If my mother where to die would my brother have to repay the £120,000 to my mothers estate? My brother made a verbal promise to repay the full amount back within two years but has failed to do so.
my brother used the money to part purchase properties that he rents out.
Is there anyway I and my other siblings can force him to return the monies?
This situation distresses my mother greatly. My brother claims he is remortgaging his rental properties, he has been claiming this for 4 months and blames Covid for the delay
thank you