Dynamic upper and lower boundary

Hi everyone.

I have a problem with my dynamic data sheet where I would like to add a upper and lower boundary. I have attached a xlsx file.

The data for the data table will sometimes be updated by import (the function is not in this test sheet), so the table will be expand vertical over time.
I would like to add an upper and lower boundary line (fx upper = 7 and lower =2) on the graph that automatically extending as more data are added. Therefore the drag option where data is copied down to the next cell is not an option.

I would like the boundaries could be operated from one cell and not have to have columns for the upper and lower limit.

The last goal is to be able to adjust the value of the boundaries (yellow cells) so the boundaries change on the graph.

I hope someone can help me :-)