I've a CSV file with the following format (`;` is the delimiter):

 KEY;..;..;..;..;id1;..;..
 SUBKEY;..;..
 SUBKEY;..;..
 SUBKEY;..;..
 
 KEY;..;..;..;..;id2;..;..
 SUBKEY;..;..
 SUBKEY;..;..
 SUBKEY;..;..
I need to take the `id` (6th column) from each line starting with `KEY` then append it to the following rows starting with `SUBKEY`. So the result should be something like this:

 SUBKEY;..;..;id1
 SUBKEY;..;..;id1
 SUBKEY;..;..;id1
 
 SUBKEY;..;..;id2
 SUBKEY;..;..;id2
 SUBKEY;..;..;id2
Any idea how this can be done in bash script?