Hello excel 'top experts' :)

Another challange on my desk (and something to learn about combine data).
Hopely somebody can help me out.

I've got a sheet with column A till CH
The sheet has several duplicates in rows because in the columns M - BJ and BP - CH there is data showed in one of the columns but in a separated row.

For example

Column M N O P
Row1 a
Row2 b
Row3 c
Row4 d

That should be

Column M N O P
Row1 a b c d

But,.... there are also rows that don't need to combine.
For make the difference in yes/no to combine and till what row I made some codes in column A. In column B is a key registered which reflects a combined created unique value to show which rows belong to each other.

Column A B
Row1 M Key
Row2 F Key
Row3 F Key
Row4 B Key
Row5 U Key
Row6 B Key
Row7 B Key
Row8 B Key
Row9 M Key
Row10 F Key
Row11 F Key
Row12 F Key
Row13 B Key

A macro should be very helpfull :)

It should combine in the row with code M all the values registered in the the row with M itself and then together with the values in the below rows where F is the code in column A and in column B the key is the same.

So in row 1 you get the registered data from row1 & row2 & row3
in row9 you get the registered data from row9 & row10 & row11 & row12

This should be done only for columns M till BJ, and BP till CH.

On the end I can delete the rows with F in column A.

regards, Johan