I apologize if I am being dense.

From your example if the user selects both Ford and Toyota then the dependent list should list Auto Pilot, Warp Drive, and Tires. This is the result I want.

But what if the user selects only one model? Wouldn't Tires only be "saved" under one of the models cases and not be available to both individually?

If the model is selected individually:
Ford>Auto Pilot, Tires
Toyota>Warp drive, Tires

If multiple models are selected:
Ford & Toyota>Auto pilot, Warp Drive, Tires

I don't want Tires listed twice if both models are selected, just have Tires be available to both modules individually AND if both models are selected together.

Is the only way to accomplish this to have a third case which which is Ford and Toyota and have its own list?

This is the best I could come up with and would be very difficult in the end.

Case "Ford"
DropdownListEntries.Add "Auto Pilot"
DropdownListEntries.Add "Tires"
Case "Toyota"
DropdownListEntries.Add "Warp Drive"
DropdownListEntries.Add "Tires"
Case "Ford", "Toyota"
DropdownListEntries.Add "Auto Pilot"
DropdownListEntries.Add "Warp Drive"
DropdownListEntries.Add "Tires"


Thank you as always!