This question already has an answer here:
No, this is not a duplicate:
I'm talking about all MSO questions in the suggested questions list, while @MadScientist wants to be able to view the faq posts on all per-site metas. That's a difference.
We have a lot questions on child metas that could be easily closed as a duplicate of a MetaSO question. While implementing a cross-site duplicate function might be a nasty job, perhaps it's easier to suggest "Questions that may already have your answer", also from MetaSO.
So, when one is going to ask a question about the difference between declined and disputed flags on a child meta, he would get a list of questions which includes What is the difference between disputed and declined flags?, which is a MetaSO question.
This would help us get better answers and in the meanwhile clean up the meta sites.
The chat with an expert hype of today has shown that this can be really useful: here, here, here, here, here and here are all child meta questions about Chat with an Expert. People have wasted there time making and cropping screenshots, explaining their questions, answering them, etc.