Userform: delete all content through double click but not the highlighted line

Hi,
I have a worksheet in whichs Column A Cells , there is corresponding string content in Col. Z. Some cells of column Z contain of many lines (up to 100 line) which i want to reduce to one. I want to select one line through double clicking in the listbox of the userform and all other lines should be deleted and only the clicked one should remain. Code should then jump to the next non empty Z cell.

Columns B, C, D, E, F, G and H should also be shown in the userform and they should be live editable. I have attached and example file with userform and example data.

I will be very thankful for each help.

Unfortunately there is no code yet. I have only the userform!
I have changed now the size of the userform. Its smaller now!
thanks

I can't write the code myself. I have no idea of VBA. Therefore i had posted this problem in the "Commercial Services Exchange" of this forum because I didnt expect the solution here. I had posted it on 26th of December and there is yet not a single answer.

So i simplified it and posted here in the non commercial area with the hope some one can help.

I can try to explain if somethig is not clear.

thnaks

Thank you very much for taking the time to understand my problem.

The userform i have posted is not a must. It must not look like i have made it. Important is that i can selectively decrease the lines in Z column.

Thanks