Collaboration/Remix Etiquette?

[AAAlex]

Hi, been lurking for a bit.

I've come across some sequences I'd love to mess around with and add on to, so I was just hoping to get some guidance on to approach playing with other people's tracks. Are you supposed to message people for permission to create a sequence based on their original?  Or do people just sort of jump onto whatever they take a fancy to as long as you make sure there's a link back to the first sequence?

edit any of mine. yes, even things form the Speedyverse OST, just nothing of TPOL right now :3