Thank you so much for all of the further advice. It is so lovely to see my old friends on this thread, such as billybagpuss and RandomMess, who gave me so much sound advice on the last thread.
First, regarding investments, I can see why some people have suggested premium bonds but, also, as one pp said, this could lead to inequality if one DGD struck lucky and the other didn't. However, I have spoken with one agent who deals with casked whisky, having made some on line enquiries, and he is going to send me some further information and suggestions. I will also speak to my BIL.
I like the idea of a bloodline trust, which someone else suggested and am making enquiries about this. I am 61 and, as far as I know, I am in good health, but my mother and maternal DGM both died at age 62 and, of course, DH was diagnosed at that age, so I feel - hopefully irrationally - that the portents are not good. I need to do what a number of people have suggested, which is to take professional advice and do some proper financial planning, so that my DDs are taken care of, and that any DGCs also have something. I absolutely will make sure that DD2 and DD3 and any of their DC, if they have any, are not disadvantaged. At the same time, if I don't 'fall off my perch' shortly, I am conscious that I need to provide for future care, in case I become physically or mentally incapacitated. For this reason, Powers of Attorney are a very good idea and, again, this is something which I am looking into, but I also need to keep some flexibility. I am so grateful for all of the advice.
I am afraid that whoever suggested that LB was biding his time, until DD1 has been allocated enough time for grieving, may have been right. Since the exchange with SIL - when I just emailed back and thanked him and said I would have a rethink - the communication with DD1 has not been quite the same. Yes, she is still in touch, says she misses DH etc, but there have been no photos or videos of the DGCs for two weeks. I know that isn't very long, but to put it into context, I was receiving them virtually every day before. Maybe it is just coincidence or maybe it is the beginnings of manipulation, we shall see.
And that's the sad thing, which I have already told DD1, that I am afraid to really love the DGDs, in case they are taken away from me, as their mother was.She may be back but I am also afraid to really love and trust again. I mean I do love her, but I am wary of being hurt again, although nothing can hurt more than losing DH. From that point of view, I am not bothered at 'falling off my perch', not at all, although I wouldn't be as brave as he was if it were something similar. I just don't want to leave a mess for the DCs to clear up after my death.
DH didn't express any wishes or leave any bequests in his will. I am the sole beneficiary. But I thought it would just be nice for the DGDs - and any subsequent DGC - to have something of their own to remember DH by.
DH didn't want DD1 to be disinherited as he felt, and I agree, that it is a terrible message to send to a child after your death, when there is no chance of a reconciliation, not that we are estranged at present. DH wanted to give them each a sum of money for use during their lifetimes and suggested £100k, so ironically that is what they will be getting, albeit by a slightly different route. We had agreed that each DD would then inherit a third on the second death, but each third to be divided between each DD and any DGC. So, as things stand at present, DD1 and DGD1 and DGD2 would inherit one ninth, and DD2 and DD3 would inherit a third each. That way, DD1 should not be upset, but her share is limited.
I am also concerned that DD2 and DD3 should have somewhere to live and that, so far as possible, the family does not split any further after my death. I suppose it is what we all want, but even a couple of hours on MN shows that this is often not the reality. I think that Yoni is sadly, right, and that I will always have to keep DD1 at arm's length.
Regarding DD1's course, it was all going so well, she was really enthused, even spoke about wanting to teach excluded children, as she thought Classics might 'save' them. She had managed to arrange her second placement at a private school back where she lives (there are very limited placements for Classics, unfortunately, some of her short have not been teaching Classics at all). She was quite excited, saying that if she subsequently found a full time position, she would be able to send the DGDs there at reduced fees. She seemed to have formed a close bond with her tutors and mentors and just seemed different. The Covid struck again, she is back home, not seeing anyone. She has quietly dropped the idea of teaching and said to me that she and LB had thought of buying a smallholding, probably in Scotland, where property is cheaper, as they like the outdoor life and want to live off the land. She asked me what I thought, and in such a way that I gained the impression that she was hinting that I might want to contribute, but sometimes I fear that I have become very cynical and suspicious where she and LB are concerned. She said that they were worried about 'hyperinflation'. I said no need to worry, they have a mortgage free house, that there is always a demand for Physics and Classics teachers, and that they should go where the jobs are. Of course, when they have the inheritance, this might well rekindle their plans to move. And, genuinely, good luck to them.
Sorry this is so long!