Thank you all for your feedback. We have implemented this idea now based on your feedback. The idea has been implemented in our "Married Pairs" feature.
You are testing a travel reservations site.
A customer may or may not rent a car (so parameter values for Car Rental could be: "Rent a Car" or "Do Not Rent a Car"
Values for Type of Car Transmission could be: "Manual" or "Automatic" or "N/A"
Simply hover over a Value name and then click on the green arrow that appears when you hover....
Select "Do Not Rent a Car" in this example. Next select "N/A." Confirm you're making a "bi-directional" married pair and you're done. There's no longer a need to create multiple separate invalid pairs.