Hmm , did he die at their home or in a hospital?
The lawyer could look into possible manipulation or influence by the family -esp if he was drugged or in extreme pain. {Dr or hospital records?}
But you don't want to rack up a big atty bill and then find out that you don't have a case/claim.

but we had to have BIL do a basic quick will 3 days before he died because until then we thought he had one at the fathers house.

We should have done a trust but things went downhill so fast and we thought things were covered.