I know two mums who did this and then both sadly died in their 30s ( one of cancer and one from Covid ). The same thing happened in both cases .
The kids went to stay with her parents while the mum was dying in hospital ( as the dads couldn’t cope and so they could be at the hospital etc ).
After the death, the kids stayed with their GPs as the dad was grieving and couldn’t cope.
Then very VERY quickly, the dads were in new relationships, moved their new partner into the family home and didn’t want their kids back, as they thought it would be “ too unsettling for them “. In one family, the kids were very young ( toddler and new born baby) , so after 6 months of not seeing their dad they hardly even remembered him.
Now these children are being brought up by their maternal grandparents , who get no money and little support from the kids dads .None of these kids will get any of the money / half of the house that their mum left them until their dad dies, which will probably be another 50 or even 60 years. Because that’s what was in the will - the surviving spouse could live there as life rent.
Now I know you are thinking “ my kids dad would never do that “. But half of all days stop seeing their kids completely within 5 years of a separation / divorce so it’s not logical to think that widowed men will act completely differently.
I also have close friends whose mum died suddenly when they were at university . She had left her half of the house to her kids , to go to them straightaway on her death. Their dad said he would “ buy them out “ and put the money into an account for them to buy flats when they graduated. Of course they agreed to this as they didn’t want him to sell the family home as they would have no where to go on university holidays and that was where they had grown up.
The dad he very quickly remarried, sold the house and moved about 400 miles to the other end of the counrty. The kids never saw the a penny of the money he promised them and when he died, the whole house was left to his second wife and then to her children.