I'd do it with VBA:
make sure the cursor is located in the first data group. Then first go
to the last column of that group (Selection.End(xlToRight).Select).
Make the cell in the next column the active cell (ActiveCell.Offset(0,
1).Range("A1").Select). Insert three columns (code is like
ActiveSheet.Range("g1:h1").EntireColumn.Select and then in the next
code line Selection.Insert Shift:=xlToRight). After you have checked
out all of the horizontal data groups you move to the vertical groups.
First of all you have to go back to the first data group and go to the
last row ( 2 possibilities: Selection.End(xlDown).Select or
ActiveCell.SpecialCells(xlLastCell).Select) and insert there three
rows according to the previous example.

Good luck