This is very glib statement. My ex gives hardly anything I have friends who are single due to being widowed, or have been left in enormous debt, or the ex has vanished or is in prison or not working etc
I think this is a difficult situation and I think you are trying to hard to help and I can see the motive. Your single parent child is clearly not spending it up! Could you invest in their career - more long term eg degree to help their earning potential.
I don’t know if explaining my situation might help ?
DH and I have combined a few children between us, my youngest sees his father from time to time but he doesn’t contribute really. DC1 lived at home and now lives independently- he lived rent free until 25 and we have had various conversations over recent years about him paying more towards family stuff. Eg he took it as we would pay for everything holidays, meals out and takeaways and he never paid for a coffee. He now out earns us and we have put a stop to the free loading - as it just isn’t fair.
We have other children at university and yes we pay for accommodation they are in hall of students houses etc - eldest DC doesn’t see this as fair - however he didn’t want to move out or move away or go to university away and left university debt free. The other DC we pay for their phones and accommodation whilst they are at university but that’s it. However their money mindset is different both work in retail part time jobs and both offer to pay for shopping etc
Eldest DC is very very money oriented and for example earns well but gave DH a book from a charity shop for Christmas and gleefully told him how much it was, it did raise an eyebrow but it’s the thought we have always said that. He paid £15 tops for everyone’s present - and literally rubbed his hands in glee like Mr Mean but we get this maybe be him or his ND or other and we can only encourage him gently out of it.
We can not compare like with like as all of our children are ND. Eldest DC moaned when he moved out about the cost of everything and then we discovered DH was still paying his phone bill and we stopped it / number 1 complained that 2 and 3 got their phones paid. We had paid his phone bill for nearly 10 years!!! We countered that his phone, accommodation, food, bills had been paid up to the age of 25 and phone to the age of 30! By 25 he had £50 K in the bank a highly privileged position. We also gifted him a large amount of money to buy.
Both 2 and 3 are at currently university doing 5/6 year courses so 1 complained this wasn’t fair. But DH & I had a frank conversations that we can’t be completely fair and equal. We just can’t. 2 and 3 are likely to be highly very highly paid / so will out earn 1. But we only paid accommodation.
Being a single parent is tough - same outgoing and half the income at least so yes I would support and invest. Because DH and I also believe we can’t take it with us. Our adult children 2 and 3 are likely to out earn 1 and we can’t compensate for that. Our eldest (and all our children - we have 4 are ND) is least likely to spend a penny, he has limited friends and social life and instead we invest time with him - listening to his moans and current intense topic of conversation, encourage skills such as volunteering etc we try to help him to do personal growth.
Having also been a single parent I can not express the total isolation you can feel. It’s not just 1/2 the earning of the others - she has the same out goings let’s say outgoing are £2 K and her income is £2 K and your children have an income of £4K and outgoings of £2K all of a sudden you have an extra £2K to save and earn interest, bulk buy (cheaper), more down time cinema etc to relax, and you get 50% of your free time on your own / so you get downtime. Your single parent daughter gets no down time.
It is not comparable.
So I would ask her if she wants to do a degree or training you can fund. I would do wrap around care from work or whatever for her (I’m semi retired) of your gran child and I would yes pay for extra absolutely - you can’t take it with her and until your a single parent you don’t get it. We have gifted DC1 money to buy a flat and we probably won’t have to do as much with 2 and 3 but will have paid for more uni, so we are trying.
We are going on holiday in the summer and all the children are coming. DH and I will pay 80% and DC1 will pay 20% (his share) DC 2 and 3 won’t pay for flights or accommodation but will pay drinks and ice creams when out and we have told DC1 he needs to buy some meals out - he is getting an expensive holiday and his own room. It’s all the little extras such as airport parking DC1 won’t consider and deliberately try to avoid but slowly he is seeing the experience is not just about money. DC4 is a teenager but has already offered up his pocket money. But you get my drift - in my mind DC1 will never be happy and we can’t treat them the same.
We are aiming and are in a position to try to assist all of them to buy a home and recognise we want and need to offer load money to avoid inheritance tax.