Tree Editable view in wizard

I have created a wizard on which after selecting the department of many2one fields generates the list of posting of employees(which is having tree view as editable=“top”) for the same departments. While re-selecting the departments the previous list of posting of employees is-sticked and a new list is added at the bottom for the same. I want the new list to be updated at the top and is-sticked list to at the bottom.
I tried this by changing the posting of employees having tree view as editable=“bottom” but the problem remains the same.

How is it generated? Are you using the same way as

Do you mean that the former lines should be removed?

If you update the list via on_change and want it top. You must insert new record first in the list.