My customer sells auto supplies and needs a simple and organized way to present options for motor oil.  Oil comes in different grades, such as 0W-5 and 10W-15.  It is sold in sizes of 1 Quart or 1 Gallon.  For a particular product, such as "10W-15 Gallon", there is one price.  

Our plan was to organize the data with a Variant Group called "Weight", with Variants of "0W-10", "10W-15", etc.  Then, for each weight, we are creating a Variant Group, such as "0W-10", with Variants "Quart" and "Gallon".  The end result is the user is first presented with a drop-down to select the Weight, then once a weight is selected, is presented with the Quart or Gallon drop-down.  I have configured the Conditional Variant Groups to work this way to hide and show the second drop-down.  

To make this somewhat work, I added a value of "-Select-" to each sub- Variant Group and set Hide for all Variant Groups except "Weight" and "0W-10".  This way, the user is presented with two drop-downs, with Weight pre-selected as "0W-10".  

If the user selects a size, everything appears to work correctly.  However, if the user changes the Weight, and then selects a size from the other drop-down, the price becomes the Sum of the two selections.  So, if I select 0W-5 Gallon at $12.00 and 10W-15 Gallon at $13.00, the price becomes $25.00, even though it appears I have only selected on Weight/Size combination.

To make maters worse, when I add the item to the Cart I see the Product listed as "Oil, Weight=0W-5, 0W-5 Size=Gallon", but still with a price of $25.00, instead of $12.00 as it should be.

It doesn't matter to us how we organize the products, variants, variant groups, etc.  We just need this to work as described in the first paragraph.  Can this be done?  Is there a better or different way?  What we are doing now seems cumbersome, anyway.

Thanks!