You can't extend the lines with data validation.
To do that you need to use a combo box where you can select the number of objects to display in the list.
The instructions in the link I gave you are very clear. What didn't you understand?
Thanks Andrew. I will try it again maybe my head wasnt screwed in right yesterday.The DoubleClick procedure tests if the cell has validation with a list, and if so shows the ComboBox. So everything should happen automatically.