There isn't such thing as "grousp". You may achieve this in several ways: you may add the bullet behavior to a family, add all objects to that family and bullet them all. You may add each object the bullet behavior and bullet them all. You may add the bullet behavior to one object, pin all other objects to it and bullet it, etc.
I would suggest the family approach. Also, for what I see in your image, I guess there are both scenario objects and interactive ones. It might be a good approach to have separate families for them, both families with the bullet behavior.
Hope this helps. Cheers!
but my english is poor
you can make a source for example ?
i want all family object bullet correct objects distance.(similar first picture topic)
Please put a source for example.