FIL care

I would say no to this without an iota of guilt. Dementia is a progressive disease and there is every likelihood it will become unmanageable in a home setting. It's unfeasible and will literally destroy your family life.

There will be a huge time delay before house sold and annex built, what is the plan before that is done?

Who will look after FIL when he needs care? If you are getting carers he may as well stay in his own home or go into a home as I assume his health will deteriorate

OP, you know that your FIL is only going to get worse. He will never improve from how he is now. If you're having doubts based on his current condition, imagine 5 years from now. Protect your children and your DH from himself and say no to this. Your FIL needs a care package where is is safe, so no toys as trip hazards, bed guards in place etc. This is not your family home.

If your FIL ever needed residential care (and that is extremely likely with dementia) then there are legal implications if he has invested the money from his home into your property. This could result in the council coming after you for the money and putting a charge on your house. Look into this carefully and also 'deprivation of assets'.

On an emotional level, are you 100% certain you can cope with this? It's a huge burden (I've been there) and kinder to say no before it starts than further down the road.

Practically, do you or your DH have the ability to care for someone who is not always lucid? You will need to provide 24/7 cover between the two of you, even with carers coming in to provide physical care.

In practical terms, the build an annex plan isn't going to work. Hospital will want him out a lot quicker than that. So you would need to find an interim solution for him while the annex was being built (you're talking months rather than weeks). If he's delusional in hospital, then every move is going to make him more confused and frightened - remember the delusions are his way of finding an "explanation" for things that are scary and confusing.

Carers at home will only work for so long. So it's arguable as to whetehr the best solution is for him to return to his own home with carers and in due course go into residential care or whether it's better to go straight into residential care. When my very independent father had a sudden decline followed by a spell in hospital, he managed 2.5 months before needing to go into a nursing home.

The most difficult thing about caring for him at home was the unpredictability. You couldn't even settle down to an evening watching TV because you were always on edge waiting for the call to sort out some problem, whether it was something trivial or a fall with lots of blood and a 999 call.

typical of that generation a bit sleezey and a bit racist. That's rather a sweeping generalisation. I have many friends in their 70s and 80s and I wouldn't call any of them sleazy or racist.

The care of an elderly person is relentless. I know so many carers who have been totally broken by the stress. You owe it to your own health and the welfare of your children, not to do this. Having spent 10 years taking care of MiL, Mother and Stepfather, I have lots of experience in how soul destroying it is. I would give you exactly the same advice even if you were single and childless.

To be honest, having you, your DH and two small children and FIL living together sounds like a recipe for disaster. Major considerations would be if your kids are going to be negatively affected and what happens if FIL decides he doesn't like his carers, and that you don't particularly seem to like each other even from the off.

I'm in the same boat as you with having young kids and difficult older people and it's bad enough without having them in the same house!

FIL being in hospital is maybe a good time to work out a compromise option like him moving into sheltered accommodation. But I'd be really worried if you went down the extension route that it would be impossible to get him to leave if it wasn't working out.