Insert row below each selection

I need help inserting a row below everytime i select from a dropbox.

i.e whenever i make a selection from the dropbox, another row will be inserted below it.
however a row should not be added if a selection is already made on that row.

so when i pick a selection from cell 3B, a whole row will be inserted below 3B.
but when i make a selection from cell 3C, since there's already a value in 3B, a new cell would not be inserted.
the row should still be within the 2A merged cells.


pardon if my description is too vague. i'm an excel noob. i've attached a picture and the excel file hope it helps. =X


Many thanks!

I've kinda found a solution, but it needs fine tuning.

ActiveCell.Offset(1).EntireRow.Insert

However when i make a selection at the next column, a row will be inserted as well.
e.g 5 selections from dropbox in 5 different columns, will insert 5 rows.

is there a way to limit it to only one row inserted per 'active row'?

I was thinking if we can do a, if adjacent cell value > 0 , delete row.

i came out with

=IF(B4:B6722>0, ActiveCell.Offset (1).EntireRow.Delete)

but couldn't get it working. HELP?