I have two children, my partner has three (our two and an older child).
We were thinking of willing each other 50%, and splitting the rest equally between our children (so 1/3 each via him, half each for me).
I've recently begun to think that my partner's oldest child should also have a portion of mine, to reflect their share of 'his' money if any is left when I die.
I was thinking 20-40-40, with the 20% reflecting 1/6 but rounded up.
Similarly, 'my' two should probably have a slightly larger share from him on his death, if I died first - to reflect my contribution to the marital assets, so that they get a bit more to reflect my contribution. But at that stage it gets a bit too complicated too work out what their share should be.
This is why the 50% to the partner, then equal split to the children of the partner feels fair to so many - because being precisely fair can be extremely complicated and then not feel fair.
A few points which aren't obvious:
- the male partner is likely to die first - and then the female partner may have all the rest of the marital assets that go to them spent on their care.
By doing a split of 50% to the children, 50% to the partner, at least the children of the father end up with something rather than waiting the several extra years until the mother/stepmother dies.
So things are probably better overall for having a social rule of half to the partner, half to the children - rather than leaving everything to the partner and hoping that they will split it between all children in the blended family.
- my stepchild's mother has property, child maintenance has probably helped towards building that up. Their grandparents also have property. I want the outcomes to be roughly fair rather than the percentages to be equal in our wills but not equal in practice.
If it turned out that their mother lost her property, or they were disinherited, or that they are the only one to care for me when I am old and challenging, I might look again at the division.
But fair doesn't mean equal, just as money doesn't equal love - which is why a non-equal split might sometimes be better.
- stepmothers often make contributions, or limit their earning potential to benefit their stepchildren in ways which are not visible - reducing working hours, relocating, whatever. Many posters are assuming the OP's father is the one who earned the money. But even if it was the case that the female partner earned less in a relationship, it doesn't mean that that assets should be divided on that basis.
Hopefully, I'll have spent it all before I die so all of this will be notional - I would be happy to leave an equal split of nothing!