How can I solve variant picker issues on my product pages?

[eausti20]

Hello, I have recently added a variant picker to some of my product pages in conjunction with the restock app and am having some issues with it. There are some variants that are not available but if I delete the individual variant you can still pick that option and the notify button just automatically defaults to a variant that is available. I want the variant picker to grey out or make the unavailable variant not clickable.

The variant picker also defaults to the first option but I want it so you cannot hit notify me unless you choose the variant. In otherwords I want a blank default that you then have to select in order to proceed. 

For more understanding: I have a product that is specific to trucks. So first the customer picks Make, then Category, then Bed Length. Some makes do not have all categories and some categories do not have all bed lengths. I do not want customers to be able to pick those options that do not exist. Thank you!