How to make a macro who will, depending on code and values in sheet1
decrease value of same code in sheet2 and copy value of cell d1,

Sheet1:
A B C D
1 M009/05
2 1234 5
3 2345 1
4 5678 2

(Note: value of cell D1 is 9 but format is "M"000"/05" - p.s. number is
increasing automatic, that is ok)

--------------------------------------------------

Sheet2 (Before):
A B C D E
2 1234 100 M001/05; M002/05 (Existing values)
3 2345 100 M006/05
4 5678 100

Sheet2 (After):
A B C D E
2 1234 95 M001/05; M002/05; M009/05
3 2345 99 M006/05; M009/05
4 5678 98 M009/05


Help!