Logic to segregate a field

Hi everyone,

I am stuck in a requirement wherein I need to segregate a field base on some values. w is The screenshot of what my debugger is below:

The fields are from table AUSP. My requirement is that I have to concatenate the values of ATWRT for recurring values of ATINN (as highlighted above) and display the remaining values of ATWRT for non recurring values of ATINN. The output of the above table should be like below:

Just like for the 9 series above , the same goes for the rest of the series as well. So for the 12 series it will be like :

Can anyone please help me out with the logic for the above ?

Regards,

Manish