I just discovered that all team sites are stored at the same /site/ url as communication sites. That of course is a problem. I changed the setting so that new team sites are now stored on the proper /teams/ url.
However, i can't seem to find any documentation explaining how i can move all the existing team sites away from /sites/ to /teams/?
As an alternative i can't find out how to link an existing team up with another team site either.