I think the word ‘inheritance’ is fuelling the detractors. It’s not really an appropriate description is it ? The house wasn’t an inheritance, it was a gift. If it had been a cash gift and he was asking for it back the replies would be very different.
And I haven’t ‘missed’ anything, I just don’t happen to agree with the majority, a good proportion of whom can’t be bothered to read the OP’s posts properly - if they had, they would realise the property is already sold and her dad isn’t objecting to downsizing, he wants money from the profit as well and the only question the OP has asked is if she should give it to him. But in true MN fashion, people are painting the OP as grabby and selfish, while completely ignoring the fact that it’s not the OP who has put her dad in this position - he did that himself with his reckless spending.
So, based on the facts I don’t think the OP should give him any money as a lump sum. The likelihood is that his creditors will take it, or he’ll use it to get into more debt. The OP has told us he already owes more than the house is worth.
The OP’s mum was instrumental in setting up this agreement because she saw him for what he was and realised that, left to his own devices, he would make them homeless, so she put their assets in the OPs hands. If you read the OPs subsequent posts it seems clear that he has had income of his own at some point, as she says he can ‘no longer’ afford expenses. It’s also clearly stated that his reckless behaviour hasn’t changed, so if he’s wasted his own income instead of taking care of his responsibilities in the way of living costs, for which he has form, and which nearly cost them the house, he obviously hasn’t a shred of remorse and has no intention of changing. So why should the OP subsidise him ?
The OP has kept a roof over his head - the alternative for her dad would be homelessness and that’s where her obligation ends. Dealing with this level of financial abuse is exhausting and the OP has likely seen and felt its’ effects throughout her childhood. She’s still dealing with it years later, she’s trying to do the best for him but she doesn’t want the rest of the money squandered in the same way as every penny he’s ever had his hands on.
You wouldn’t reward a child with more money if they had wasted what they had. You’d want them to learn the value of money from their wastefulness. OP’s dad hasn’t learned so the last resort for the OP is to save him from himself and protect her own interests. I, for one, don’t blame her for not wanting to enable, or finance any more of his appalling irresponsibility. The OP isn’t the bad guy here, as much as some posters want her to be.