"...the likelihood of an 1975 Inheritance Act claim succeeding is strong."
I think that I might disagree with you here.
Unless there is an issue like promissory estoppel, then I really don't think that you are correct.
Are you perhaps thinking of something like Isaacs v Green [2025] EWHC 1951 (Fam)?
In that case the mother's estate had been divided between her two daughters and nothing at all was left to her son who was living in the deceased mother's home.
The son was retired, living on just a state pension, and living in the mother's house.
The executor lived in the USA and wanted the money from the house to improve her living conditions.
The Court therefore had to consider the circumstances where both claimant (the son) and defendant (the daughter who was the executor) were in financial need.
The daughter claimed that the son was excluded from the will because his mother disliked him.
However, on the balance of evidence the court found that it was more likely that the deceased had been concerned about the state of the claimant’s deteriorating marriage on any estate finances. Although the court did not speculate as to why the deceased did not alter her will after the claimant’s divorce was finalised, it accepted that the relationship between the two was ‘friendly’ in the later years to her death.
The Court said that normally, a life interest would be appropriate but that didn't apply in this case and said that the son was entitled to 25% of the estate and that the two daughters would get the other 75% shared between them.
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Maintaining a child, of itself, is not generally enough to warrant more than an equal share of the estate.
There must be an additional factor that an adult child must show beyond just being a child and having financial need.
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Or perhaps are you thinking about Howe v Howe [2025] (unreported)?
An estranged adult daughter (the only child) was awarded £125,000 from her late father's £1.4 million estate. This was after she was excluded totally from the will.
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A serious question, I would be really interested why you say this. For non-spouse applicants like adult children, the award is strictly limited to what is required for "maintenance" (ordinary living expenses), not capital enrichment.
"It would therefore be wrong to believe that if she dies intestate that the estate will be split four ways."
I really am confused about this. Why would one of the children, absent any serious medical needs etc, require more than an equal share of the estate?