I think that sometimes finances change either for the better or worse and as a consequence plans can change too.
I'd expect any teenager as a minimum to be taking in a summer job to earn some cash to partly cover their leisure expenses. Remember uni fees are both tuition and living costs. As a parent, I'd be wanting to contribute but I'd expect to see some active engagement in a financial sense from the teen too. Surely they shouldn't be passively sitting and receiving full fees for both the cost of course and living without taking any responsibility? How would that help them start their journey to financial independence?
In our scenario we have been saving for our kids. By the time each goes to uni, there will be about £75k available for each. There are a couple of options for us (and OP) in this situation - we can fund the course fees and living cost fees up front and not apply for any loans. Most of the money would be gone by the end of course and any left over could be used towards house deposit. Alternatively, we are more likely to apply for at least the course fee loan and pay most of each child's living costs,mwhilst also expecting them to work in holidays and contribute tp something towards their living costs. At the end of the course, depending on career path and likelihood of earnings making loans repayments high and likely, we might then pay off some of the loan or all, or we might keep it and child will get most of the money later for house deposit.
Either way, the cash is there for the child to benefit, but the way it's spent will be determined by a number of things.
In OP's scenario, I wouldn't see a problem if they asked the child to use some of their inheritance for uni and reduced their parental input. The reason parents pay (if they can) is becaue the kid can't. But in this case they can.
Remember, most students do actually pay a lot anyway...becaue although their paents pays the parental contribution and tips up the living amount to what's needed, most students have loans for course fees and some of their living and pay it off over many years. It's just they don't pay it off at 18.
So I'd see this inheritance as providing lots of possibilities, to be discussed between alrents and child. I do t think OP was looking at paying £60k to over living and course fees over 3 years anyway, just the parental contribution. So, if this was perhaps £6k per year, perhaps the child coukd pay half and the parents pay £3k. It's only using £9k of the inheritance.
And then it's up to the kid. Do they want to use their inheritance to pay off the loans for course fees and the chunk of living costs which were borrowed? Well their inheritance allows them to start debt free if they want. It they can choose to keep it for a bisque deposit. That's fine too. Either way, they start with an advantage most don't have and are very fortunate.
If the family are struggling to pay uni costs, and suddenly this windfall has come their way, I think it's fine to reevaluate their spending plans. There's no need to continue as if the windfall hadn't happened. It doesn't matter that it could have happened 3 years later after parents would have paid. It could equally have happened 3 years earlier before they started paying. It's actually happened now, so should be factored in. The kids are fortunate to get a gift, and it will undoubtedly make their lives easier, and if at the same time the current burden in parents is lifted a bit too, why wouldn't you? And I'd imagine most upper teens woukd see it like that too.