I Think there is no way you can get out of this, unless the house is valued very low. I Know if a couple got savings of 16,000 or lower, it wont affect there benefits.
Maybe you're best bet is to contact one of the companies that do the Buy & Rent scheme. They normally give you 70% of the market value of the house e.g. 60,000 x 70% = 42,000. And you can live in the house & rent it from them. I Know the amount you & you're sister will get is over the threshold the benefits allow, but you shold end up with around 20,000 each.
Check it out i would.
p.s. You didnt say if you & you'r sister are married or have a partner that you have declared living with you, if you have thats even better for the threshold.
Good Luck