Yes i get that, I shouldn't have mentioned AS but I was generalising. I was saying she can adapt the A-level paper, by just doing questions on the topics she's done. So I don't know her exam board, but for example let's say she's done all of topics 3-6 but not other ones, let's say those topics are Paper 2, but Paper 2 also has topic 7, she can perhaps only do Section A or B, and then cut down the time accordingly (because obviously she hasn't done a full paper). The questions will still be to A-level standard, she can just adapt what she does, so I'm saying you can still use the offical past papers for practice if you want. Just only do what you can, so only do the topics you've done, and then just do those questions. Normally if you Google 30 marker or 25 marker in x topic for x subject for x exam board you'll fine free questions people have done, or teachers have made up (YouTube is great for this). So you can also do that, if the issue is that you can't find any 20 markers (or the equivalent) for this topic, on any of the past papers.
Also Chatgpt is also great for this, just give it the officak specification, and say what specific topic you want questions on and the form (so 10 marker using explain or 30 marker with historical sources etc), give it an example of one (from a past paper etc) and it will make really realistic ones for you, as long as you give it the right detailed info. It's also been great at predicting topics for the final exam, if you put in all the topics that have come up since the original exam, like per question so q1 was x topic etc. I know that this year it worked for some people I know, and multiple times predicted more than one right question. Obviously don't completely rely on this, the people I knew didn't trust it fully, did lots of proper revision, but actually after it got many right, found themselves annoyed they didn't trust it.
Though there's no issue with what you did, just saying you don't necessarily have to buy them, unless you want to. It sounds like they were useful and I hope the exam went well for her.