Arranging stuff

[gleeok]

Lets suppose I get 2, 3 or more versions of the same piece, mix them up and add a little bit of my own "creations" (supposing the mixing would be my creation already). Would that be considered an arrangement by me? Or should I put the name for credits of everybody involved? How does that work exactly?

In sum, is it alright to take elements from other arrangements like that and work with them all to create a whole new one?

I'm wondering what is considered using something as referential, simply stealing or using as inspiration, in music writing.

Thanks for your attention and your comments in advance.