Wow - so now the MIL is going to be "on the doorstep" demanding the bank statements and will be "angry ad sneaky" - and the OP is being urged to "hide the documents from her DH as he could be "in the fog" with his mother! And OP shouldn't be going out apparently and "leaving DH to "fend off her anger on his own" - it's his mother FGS! Oh sorry I've just noted he's "damaged and blinkered by this evil old cow" and he could give her what she wants.
And MIL is apparently "very toxic" and the DH needs counselling! Someone feels sorry for the poor GIL even though none of us know the quality of care she is getting from her daughter.
I think there's a fair few "blinkered" posts on here. None of this OP holds together. I wonder if the OP will return to respond to the issues I raised - probably not. All this stuff about bank statements is ludicrous to be honest. Don't any of you realise that when you transfer money to someone it shows up in YOUR bank statement, so the MIL should have these details on HER bank statements, and if she's lost them the bank will supply them for a modest charge. It's all a red herring. The other issue is the allegation that MIL got her mother to change the Will. That wouldn't be possible as she is suffering from dementia and would not have "capacity" and no lawyer would get themselves into possible fraudulent activity.
As always at the mere mention of a MIL out come the MIL hating brigade with all sorts of insults against her - I often wonder if these are people who hate their own MILs.
Of course I have no way of knowing anything about the truth of otherwise of this matter and it may be that the MIL is being dishonest and is all the things she is being called by people who don't know her! However 80K is a substantial sum of money and if the OP has reported the matter to the police they should have questioned her in relation to the fraud and if there is sufficient evidence, contacted the CPS to ascertain if there is a good chance of a prosecution if brought to court. If so they would charge the MIL with fraud and take her before a court, who would almost certainly grant bail and her the case would be heard in the Crown Court at some future date. That's the way it works, so the OP doesn't make any sense to me. There's more than a whiff of a somewhat vindictive DIL here, but then that's just conjecture.
And please don't come on telling me I "stick up for all MILs" because I don't or "I'm not giving MILs a very good name by my attitude just because I'm a MIL" as I've heard it all before.
I'm really surprised that so many posters are just swallowing this OP whole and I think the reason is because it's a MIL in question.
So please OP can you come back and respond to the issues I've raised?