Concatenate two rows into one drop down? Not order them though

Ok I have two rows:

Then I have another one:

However, I don't want them combined on top of one another.

I want it so a person can select like so:

Original Performance NorGrip Grade

Gold Blank Disc Grade

Gold Blank Disc Dimensions

Truckbed Liner Kit (no value in the other column)

The truckbed liner kit has no attribute value in the column so I would rather the option not show at all... So as long as the attribute column is filed, combine the two and show it in a validation list..

I know how to create lists and then make them validation lists, but this is stumping me..