Better choice for a duplicate

Question

I just found a question (Q1) that was marked as a duplicate of another question (Q2). The core question being asked in Q1 didn't seem (to me) to be a duplicate of Q2, as Q1 was broader than Q2's very narrow focus. But, I did notice a third question (Q3), of which Q1 seemed to be a clear duplicate. So, I'm now wondering whether it would be appropriate to flag Q1 as a duplicate of Q3 instead of Q2. All three questions are 3+ years old, so I hate to dig them up. But the vast, vast majority of people visiting Q1 wouldn't find Q2 to be a satisfactory answer, in my opinion.

EDIT
This paragraph was a feature request until devRicher pointed out it exists: More generally, if Q1 and Q2 are sufficiently different from each other to not be considered duplicates, and Q3 lies between the two (e.g. due to insufficient specificity or by asking more than one question) such that the duplicate tag with just Q2 isn't likely to help the vast majority of visitors to the question unless both duplicates are referenced, the duplicate tag can be updated to cite both Q2 and Q3.

Answer 1

All three questions are 3+ years old, so I hate to dig them up.

That's absolutely fine. Instead, please do dig up old questions as dupes. They are easily forgotten and if someone takes cares of that, it's finally done.

Alternatively, the duplicate system could be allowed to mark a question as a duplicate of more than one question (this isn't already a thing, is it?)

It is, actually. This is exactly what happens if you mark Q1 as a duplicate of Q3 and Q2. This is how it would look like:

So, I'm now wondering whether it would be appropriate to flag Q1 as a duplicate of Q3 instead of Q2.

Please do so. If the question is a duplicate of something else too, but Q2 and Q3 aren't duplicate to eachother, this is the only right thing to do, resulting in the question being marked duplicate of two questions.