This is the Parenting meta discussion equivalent to the same question on Meta.Law.SE, which as of this posting is featured at the top of the top questions list there. Some of the discussion there might be informative, but I don't want to assume more connection between the communities or how they operate than is really accurate.
In the Help Center, we have the standard Stack Exchange verbiage:
You should only ask practical, answerable questions based on actual problems that you face.
Is that strictly true on this site?
On Law.SE, questions that specific are actually off-topic because they're seeking legal advice for the asker's specific situation, and some of the top-rated questions are hypothetical or historical.
Interestingly, How To Ask could be read to imply that a hypothetical question (if asked well) is useful for the community.
Make it clear how your question is relevant to more people than just you, and more of us will be interested in your question and willing to look into it.
She also refers to this answer in this discussion on the limits of subjectivity. That meta discussion came out of this question which was about a factually accurate real-life problem that somebody else actually faced (but which I and perhaps other readers might want to be prepared to face in advance), and was therefore subjected to the criticism that "If it's not based on an actual problem you've faced, then it's not on topic for this site." That critique was restated and expanded on here.
The impression I get is that even if I know somebody who is facing or has faced a particular problem, unless I am personally facing it myself, it's off topic and should not be asked on this site. Similarly, it is not appropriate to ask questions about things that may happen again in the future that one wants to be prepared for, unless they have happened to the person asking the question in the past or present as well. Is that the language and policy we want?
Here's a meta discussion for the bold question above.