It appears to me that you can't do it with overlay lines but perhaps you could do it with XY scatters as your overlay if you add more columns of data to give both the X and Y coordinates of the overlay info.

Alternatively, you might consider a different chart type to display the data. If it was me doing this, I would avoid the overlapping charts and try to do it with these two techniques.
This is the look for each column/line overlay: Overlap Graphs in Excel - Actual v Plan/Target - YouTube

And combine it with this methodology to get the second column and overlay sitting beside it Excel Column Chart | Replicating COVID-19 Overlapped Bar Chart - YouTube

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Andrew Lockton
Chrysalis Design, Melbourne Australia