Thank you for all of your replies, especially at a time when you are probably all so busy.
First, regarding DD's health, I am worried it would backfire if I said something and DD has sent me a couple of messages to say that she is resting and improving, but there is some way to go. She is on strong painkillers and antibiotics. I have thought of visiting and part of me wants to jump on the next train, and of course I would want to help her in any way I could - but I know that an unscheduled visit would cause stress to her at a time when she needs to rest and get her strength back.
I have not yet met DGD1, who is now nearly 18 months old, and DD has said that it will be 'very emotional' when I do. She has also had a long conversation with DH in which they agreed that the dynamic could be 'tricky'. I have never visited her house and she did not even give us her address until earlier this year. She seems to be anxious about what we will do when we visit, as she has mentioned this a couple of times. I have said we don't want you to entertain us, we just want to meet DGDs and spend time together, read to DGD1, help bath DGD2, all very low key, we don't want to impose on you in any way. She said we can 'see the house', and go for a walk, so I am wondering if SIL has said that we can have a quick look around the house and a cup of tea, but that is all. She mentioned visiting some steam railway, which seemed a bit random, but now I think maybe she just wants to find somewhere to go, away from the house, because he doesn't want us there. My gut feeling is that he bears a grudge for the time when I made him leave our house, so we are not welcome in 'his' house. The situation will be further complicated if she can't drive. So, I think it is better to wait a few weeks and agree a specific date.
Rachel, I think you may well be right that SIL has Aspergers and he also told DD that he thinks he does. I don't want to put labels on things which I don't fully understand but, for example, SIL has very high cognitive skills (first class engineering degree) but struggles in other areas, particularly in engaging socially or in areas of emotional intelligence. I think this is why he tries to analyse people in a scientific way - by reading books and applying the relevant criteria in order to reach a character analysis. However, having reached the conclusion, he is convinced that he is right - everyone is black and white to him, there are no shades of grey. He liked me until the time I made him leave the house and withdrew from the property transaction, but now he sees me and the rest of the family very much in 'black' terms.
I would say that there is also an element of paranoia. They spend a lot of time reading and watching programmes about conspiracy theories, which they believe. DD said the reason that they did not give us their address to start with was that we might try to get their house because we were lawyers, and they did not tell us about DGD1 in case we tried to take her off them.
SIL is not religious at all, but he has far right political views and I would say that he also has misogynistic views. DD and he have a relationship where she does all of the traditional 'wifely' work and he like working on the house, quite complicated DIY projects, which he takes a long time over, but I assume does well. DD seems to look up to him and he regards himself as her protector. He intervened with the tenants in the house she lived in, even though he wasn't a tenant, and now he wants to protect her from her family, at least that's how it seems to me.
Malta, I am sorry to hear about your experience but so pleased that you managed to escape. DD was brought up in London/SE and is the first of her contemporaries to either marry or have a child. SIL and DD live in the NE now (He doesn't like 'posh southerners' or 'yuppies' ). I share your concerns as to whether she will cope with the course apart from uprooting SIL, two very young DC and two dogs to the other end of the country.
Ruffle, I take your point, but DH and I have been happily married for many years and I would describe us as very much equal partners. DD2 and DD3 are both strong and independently minded individuals, who are baffled by DD1's relationship as well as being deeply hurt by her rejection of them, as they used to be close.
Earlgrey, you have a very good memory and thank you for sharing your friend's experience as well as for your support. I think your advice is very sensible.
heyday, I honestly don't know how they managed to live off benefits for so long, although the second property has only recently been purchased. They have no mortgage on the house they live in, so have never claimed housing benefit, but I suppose they would have obtained jobseekers' allowance and now they will have child benefit. I don't know but I assume that now that they have the second property they will not be entitled to some benefits as they will be over the relevant threshold. They do live very frugally, although they run a car. I am in despair about it, to be honest, as I have never claimed benefits, always worked, and feel strongly that they are there for the most vulnerable and needy in society. I agree that SIL needs to get a job and meet his responsibilities now he has a young family. He has done nothing since completing his BSc in 2014, apart from a six month stint with an engineering firm before quitting, as he doesn't want to be an engineer, a Master's degree which he gave up after one term, and his PGCE, but he has now decided that he doesn't want to be a teacher.