I'll try to keep this simple.
My MIL died very recently, leaving her house to DH and her belongings (inc. jewellery but still not worth a great deal) to SIL. The will was written not long after FIL died 15 years ago.
FIL was adamant that SIL would never get a penny, for a number of reasons.
DH offered unprompted to pay SIL c.80k as although FIL and MIL's reasons for not leaving any of the house to SIL are understandable, DH is a decent bloke. This will require taking out a mortgage on the house (which is owned outright, although still in MIL's name as v.early days).
DH has been living in the house since FIL died, looking after MIL - he's put his life on hold in many ways to do this.
Now SIL is demanding £200k. The house is worth maybe £300k tops.
How easy would it be for her to contest the will and force DH to sell? Any ideas much appreciated.