Copy formula from one row to another

Here is a sample sheet. The only thing I am trying to do is when I sort the data in the first sheet, I don;t want to sort the empty cells that have formulas. I appreciate your help.

With a filter on column F.

The empty cells are gone.

I marked the last row with the color red.

I can't post the example because it is 4 mb!

Filter on column F and click on empty cells. (everything without empty cells is selected en shown).