Urgently need advice for friend re disturbed DIL.

This could be a bit of a saga but I'll try to be as concise as possible. Some 30 years ago we became friends with a couple and their children who were a similar age to two of ours. I became quite good friends with the wife and she came to help out at the children's theatre group I was running. They appeared to be a very close knit family-no grandparents, aunts, uncles -and did everything together. The girls constantly fought,and argued despite the mother in particular doing a lot of shouting. The oldest girl was very surly and every time they came back from holiday she would tell tales of being raped by 'Farmer Bloggs'. Alarm bells wouid ring now. but this was 3 decades ago. I can't recall how it came about, but eventually the father was interviewed by the police regarding possible sexual abuse but no charges were ever brought. My daughter/we were also interviewed. Following this the wife shut down, seldom came out of the house, spoke to nobody and developed rheumatoid arthritis. She died 7 years later from complications of totally untreated RA.

I'm just trying to set the background, but now fast forward to 2004. The middle daughter returns to the village with her husband and baby daughter. I became great friends with her and she loved to hear stories about her mum. I think she saw me as a link to her, but we also shared a similar sense of humour and interests despite our age difference. They lived (still do) in a total shambles of a house which became worse and worse. No hot water, central heating condemned, housework and cooking seldom done and children (by now there were three) not fed until her DH came home. There was a permanent shortage of money but all she did/does was spend money on unecessary things. This resulted in a repossession order on the house which her MIL bailed them out of, along with a whole lot of other debts from time to time. She is renowned in the village for borrowing money and not paying it back. I tried my best to help her out in all sorts of different ways, but when items went missing from my home and money was stolen I had no alternative other than to cut her out of my life.

Through all this her MIL, who has become my friend, has tried her best to help and support them-taking children on holiday, buying clothes, paying for school trips, and providing rescue funding into the thousands. Despite this she has been called names I wouldn't print, and wasn't even spoken to when she came up to visit. I've actually seen the DIL make coffee for other people in the house and deliberately ignore her.

Fast forward to April 2015. My friend (the witch and MIL from hell)has now been summoned to act as nurse/companion/minder/child minder/chauffeur/cleaner and dogsbody as apparently her DIL is suicidally depressed and needs to be supervised 24/7. She is running herself into the ground trying to cope but does it for the children. The DIL is not on any medication but apparently is going to be prescribed something to take if she ever feels suicidal again. This 'suicidally depressed' young woman has managed to go out for lunch 2 or 3 times per week, has had her hair cut and coloured, new tattoos done - all sorts of social things.

I believe that this young woman is definitely disturbed but not in the way she purports to be. Everyone who knows her does not believe her current story, others have had the same suicide story played out on them. The psychiatrist she says she saw does not even exist and she's renowned for creating attention seeking scenarios.

I think my friend (the MIL) is being taken advantage of and I don't what-if anything - I can do to help.

Sorry for the lengthy post but felt the background needed to be explained in order for anyone to make informed comment.