I didn't back-read this whole thread. I have perspective to offer as someone who has already been on the receiving end.
I have one younger brother, and I've always been the responsible one.
It was pretty clear from pretty young. As a teen, I earned a little money babysitting, and it stacked up along with allowance and birthday gift money. Every so often I'd ask my dad to deposit anything more than I wanted to carry into my savings account. It might have paid for a few college textbooks, but it mostly didn't pay for whatever my classmates indulged in as teens. I certainly didn't rush out and get a car.
Brother saved money from gifts and summer job eagerly, but only until he accumulated the money necessary to buy a Nintendo.
It absolutely helped that my parents paid for my college. I finished in four years (somewhat fast for my major and my school) and, as far as my parents were concerned, under budget in terms of rent and household expenses. I didn't need to take a job while studying, which probably helped with getting through a rigorous curriculum on schedule. I did eventually take a part-time job on campus, mostly during summers. The experience, generally related to my field, was at least as important as the so-so pay. My dad, especially, resisted the idea of me taking any kind of customer service job out of concern for my safety. Whether his concern was misplaced or not, he had that luxury partly because he could pay for my tuition, rent, and groceries.
Starting out with zero debt and an employable degree meant I could start stashing straight out of the gate, and I did. With my boyfriend (later promoted to husband), we got together most of the 20% down payment for the HCOLA house we bought at age 25. My parents contributed at this point, too, whatever was the tax limit for gifts that year for two givers and two recipients. I don't think we asked for the help. We could probably have gotten here on our own, but it would have been a little thin the first couple years when we were renovating and then between jobs for a spell during an economic downturn.
Since then, we've accepted some relatively small gifts—think $100—because they have no idea what kind of stuff we'd want for Christmas. (Nobody in the family needs more stuff.) We don't argue when my parents invariably pick up the check in a restaurant. They shrugged and split the tab with my new in-laws for our <$1000 wedding, although we never planned on them doing that.
I've learned personal finance beyond "spend [a lot] less than you earn," mainly from library books, blogs, and podcasts. I anticipate but am in no hurry to inherit half of my parents' substantial 'stache, and I don't need any of it to FIRE tomorrow. It's logistics, not money, that ought to be sorted a bit better before I pull the rip cord and retire.
There's another whole chapter, maybe for an eventual journal entry/series, about Brother. He has been less successful, probably due in large part to autism that was only identified in his 30s. My parents do still assist him, although he managed to support himself for some time with a series of low-end jobs. I don't really blame him for hating jobs like those.
I don't know if he's a spendthrift, because he's never earned enough to cover expenses with much to spare. I do know he's disorganized—which is different than irresponsible or reckless. He's reluctant to ask for help, not least because of the judgement that often accompanies it. Dad definitely doesn't understand my brother, and if I'm being honest, I only kind of do.
To get back to OP's original question of giving money to their daughter: helping with tuition and a down payment when the time comes won't inevitably produce a spendthrift or "broke lottery winner" flame-out.
You'll know, and you may know already, if her money tends to go to savings and groceries, or to a spendypants car/phone/coffee habit/whatever. You'll also have some sense whether a down payment will be on something she can handle. For the right young adult, judicious assistance can be a real gift and a boost along her own trajectory to prosperity and FI.
