I'm sorry for the perhaps weirdly worded question, but here's my attempt to explain better what I mean:
In English, if I say
"We went to lunch with Bob" means that the people involved are me, Bob, and at least one unnamed third party, which is included in the "we".
In Russian, on the other hand, you could say
"Мы с Бобом пошли на обед", literally "We with Bob went to lunch", and mean only yourself and Bob.
The only other language I'm fluent in, German, has the same structure as English, "Wir sind mit Bob zum Mittagessen gegangen" would imply at least three people attending.
What I'm wondering is: Is this a trait that is linked to language relationships? Are other Slavic languages like Russian in this regard? And has there been any research on this phenomenon?