I think I just had a realization and I wanna make sure it is right...
Is the prefix "till" in Swedish the same as "zu" in German? For example, tillsammans is zusammen, tillbaka is zurück, etc? As a general rule, maybe not always (like the prefix zu in German is like toe in Dutch, but not always, because zusammen and samen)...?
Vi alla arbetar tillsammans = we all work together, but that's still different than "we work all together" which would imply maybe a lot of people doing an action together all at the same moment.
This sentence is just saying that two(+) people work together. If you're my colleague, då arbetar vi tillsammans :)