Do you claim them if you are given/awarded rank by someone other than your instructor? Is it disrespectful to wear said rank at other dojos?

This is really dependent on the structure of the systems you are involved in. This, to me, is a very easy question if the systems are different. There's no reason you shouldn't claim them from qualified instructors in different schools if you've earned them. That said, I can see some issues if it's the same style, but even then I wouldn't see too much of a problem.

You earned the rank.

When I appear in our Dragon Martial Arts Dojo, I wear the grade Given within the Dragon Martial Arts system. When I appear in an open Seminar, I can in theory wear my Shorin Ryu belt, but I don't as Dragon Martial Arts have issued my current licence. This is only one way of looking at it.

I assumed this to be about rank in the same style. It's really a question of what your instructor thinks and whether they'd agree with it.

Personally I would say it's probably OK in the same style/association if the person promoting you is senior to your own instructor. I most likely wouldn't accept promotion off of someone lower than them. But I have a great deal of respect for my instructor and would always consult him first.

In our style, testing for 1st dan and above (sometimes even advanced colour belts too) is conducted by a panel led by someone other than your instructor. In fact for 4th dan and above testing your instructor submits a request to the organisation and you then get told when and under whom you should test.

Now if it's promotion in a different style or association, they I would say its your choice whether to accept or not but I would only wear the belt when training in or representing that style.

Do you claim them if you are given/awarded rank by someone other than your instructor? Is it disrespectful to wear said rank at other dojos?

Besides my Shindokan ranks, I've a green belt in TKD under GM Young Ik Suh, and I "claim" it, when necessary, because I earned it.

Yes, imho, it's disrespectful to wear said rank at other dojo's without the expressive permission of said dojo/governing body.

It is dependent on where you got that promotion. Many of our students attend a camp every year, which is held by an isshinryu school (my school is goju-ryu) and they have many styles attend the camp.

They do gradings on the first two nights. One for colour belts and the other for Dan gradings. But that would cost extra.

My sensei is always happy to accept those promotions. as he is also one of the presenters at the camp.

The camp isn't strictly doing isshinryu syllabus but there are about 4 or 5 styles that are done. That way all students learn something from a different style and their own