capital disregard for share in home of deceased mother

I have a client who receives IS and HB/CTB.  4 years ago her mother died, leaving her property to client and her two siblings.  The property is worth approx. £75,000 (so client’s share is approx. £25,000).  The property is still up for sale and client has never declared this interest to DWP or LA.  Client has actually told me that property hasn’t sold because of the economic climate.  Client was willing to lower the price but one sibling refused to do this so the property hasnt been sold.

Client now states that an offer has been made for £72,000 and she thinks sibling will now agree to sale.  By the way, the other sibling died earlier this year.

Does client have good grounds to have the property disregarded for more than 26 weeks because of economic climate and the fact that sibling wouldnt agree to lower the price?

Is there any caselaw anyone knows of to support disregard?

What happens to the share of the deceased sibling? Was it left to the three of them as joint tenants (in which case it accrues to the two survivors) or as tenants in common? In the second case it forms part of the deceased sibling’s estate, which may bring in a whole lot more people who could object to the sale.
Has the client been living in the house since the parent’s death?
How long did it take them to get probate, which is a necessary prerequisite to being able to sell it?

The deceased siblings estate was divided between the other 2 siblings so the 2 living siblings are now joint-owners of the house.

The house has been empty since the mother died and no-one has lived in it.

Not sure about the probate issue, but client has told me that sale of the property has been possible for several years.