In case a trigger for a readied action is someone else’s reaction, what is resolved first?

I asked this question. The answer is YES.

But I’m still not sure – in such a case (i.e. a trigger for reaction being another reaction) – which reaction is resolved first, the triggered one or the triggering one?

Does the readied action interrupt someone else’s reaction that triggered it? Is there a possibility of a chain of such consecutively triggering and consecutively interrupted reactions?