Welcome to the forum.
From the little you describe of what you're trying to accomplish, I only see the need for a single table.
This single table would have two fields in addition to what you already have:
1. Item Marker (would hold values of "A" or "B")
2. "OnHand" (would hold values of "Yes" or "No")
Then there are no relationships to worry about, and no moving of records from table to table if it is no longer "on hand".
Does this match what you're thinking? Please feel free to describe what end result you are working toward.
Buttons, under "Button Setup" would be set to perform a script. From what you describe, the script would be a single step of "Go To Layout" with the appropriate layout defined.