Of course, one lives on the college campus and two are babies. But the campus kid brings his friends home with him many Sunday's after church. And the babies have discovered that they like food.
So while our grocery budget hasn't necessarily increased (yet) as we've added new family members, it has definitely not decreased because we often feed extras (one of my favorite things to do!).
Here are posts I wrote on this subject in the years BB (Before adding Babies). They may give you an idea of how we roll with food at our house...