Thank you for the responses, it is really helping. A few themes emerging so I have tried to answer these as best I can below!
Bearing in mind Covid, are you sure you and DH can find jobs?
Yes, I am pretty certain. I appreciate that the current situation makes things more difficult but this genuinely is unlikely to be an issue because of the type of jobs we do. We are very fortunate. My DH could even transfer to another branch of his current organisation in the same role and has already had this approved in principle.
If you stay, you may be closer, but you'll have less time and money overall to help. Over time, that discrepancy will get bigger. By the time your parents really need to call on you - where do you want to be? With a smaller mortgage and more disposable income to help out, or to be able to take more time out? Basically the better YOUR family does financially, the stronger position you will be in to be a good support in the future - whether with time (because you have more because you don't rely on working yourself into the ground to make your own ends meet) or with cash (because you have more of it).
I tried to make this point to them but I don't think they really understood. But I think you're completely right. Because I wouldn't need to work as much (or even at all, to be honest), then even though I'd be further away I actually think it would be easier for me to to help if needed. I could even take a career break for a few years if necessary.
How involved in his family do you think you will be? Is it too much for you?
My DH also has a small family so it would pretty much just be his parents. They're fine, we get on ok. They are definitely not the type to be popping in every day, they're quite introverted.
I would absolutely hate knowing that I could make my parents lives easier and I'm choosing not too. If you're not miserable where you are, the school's aren't awful and you're husband is ok with it, I'd stay.
Yes, I can see this side of things too
That's why I feel so guilty. The difference in quality of life is significant though. You mention schools - where we live there is one average (but not terrible, admittedly) secondary school. In the new location we could be in the catchment for some of the best schools in the country or afford private school.
If this is a life-long move for you and they are retired, would they move too? They could also move your sister close by.
They've said this isn't an option for them as too much upheaval for my sister. I think this is probably fair. Getting the place for her in residential care took a huge amount of effort and I am not sure it would even be possible to get a place in the new location.
What about your friendship networks? Are you leaving your community behind while your dh returns to his?
My close friends aren't all living where we live now, they're spread all over the country really. I do have "mum friends" here that I met through playgroup/nursery/school etc but I think they're the type of friends I could make in the new location too.
Speaking as a parent to a disabled child, I think while they hadn't expected you to care for your sister, they probably hoped you would be there to act as next of kin or to support her somehow. It's very frightening to know your child will outlive you of they're vulnerable. Have you explained to your parents the reasons behind the move? Maybe they would be able to help out. I know I would if I could.
I completely understand, and I understand even more now that I'm a parent myself. It's so hard. It's difficult to be a sibling to a disabled person but I appreciate that can never compare to what it's like to be a parent to one.
Financially, the difference is just so stark. We'd be going from having a 30+ year mortgage to being able to pay the mortgage off in less than ten years (and for a bigger, nicer house). They're not badly off but there is no way they could support us to that extent. But maybe I'm putting too much emphasis on money 