In the end, I would interpret both the school principal and the nurse to be workers of the school, just because it sounds natural, and I would use such expression. But I can definitely challenge that and prove wrong, as follows.
My question is; can the の particle be used to indicate possession (or any of the other uses it has in joining nouns) for multiple items when you have a list using と or や?
Yes it can, but depends on the situation.
For instance, If I said:
This is no different from English. Take the following sentence:
"The nurse and the principal from the school are here with us now"
It can mean either:
- The nurse from the school and the principal from the school
- The nurse NOT from the school and the principal from the school
Technically there may be a rule that takes away the ambiguity, but in real life I'd say this is subjective.
What I want to understand is if the sentence above indicates that the nurse in question also works at the school, or if it gives no indication of that, or if it is ambiguous.
For the above reason, the answer is "it is ambiguous". But there are hints. We don't really have 看護婦 in most schools. We mostly have a 保健室の先生 :) So this may be a hint that the 看護婦 is not affiliated with the school. But some schools do have nurses too, so we can't be sure. And the word 看護婦 can start a whole new debate in modern society if we start overthinking!
学校の校長と教頭 (VP or dean) が今来ている
They're both probably from the school
学校の校長と警察官 (police officer) が今来ている
Come on, the cop can't be from the school
Is there some other construction to indicate explicitly that both the principal and the nurse are from the "school"?
Not elegant but explicitly: 学校の校長と学校の看護婦が今来ている。
What about the other side of the particle? Would this be correct:
My brother's documents and mine were in the bag.
It would be correct, but only because of common sense. We know that you can't be found inside a bag. But what is I were to say:
or say like this:
Now this would NOT mean "My brother's documents and pencil's (documents) were in the bag.", would it? It would mean "My brother's documents and (someone's) pencil were in the bag".