Line connectors between columns in stacked column chart (combo chart)

[thechartguy]

Hi,
I want to create a waterfall/bridge chart using Excel such that line connectors can be placed anywhere.
Let's visualize it here (the line connectors I'd like to have are in red):

How can I add the red line connectors?

Thanks!

 

[vletm]

thechartguy​

Could You send a realistic sample of Your Excel-file, which has Your chart?