@dbltoe, I'd start by adding those additional option values via the DbIoProductsOptionsValuesHandler.

Once those option-values are in the database (so that you've got products_options_values_id's for them, I'd the DbIoProductsAttributesRawHandler to add those option/option-value pairs to the various products.

Note that neither of the attribute-related handlers currently support a removal. I've created a GitHub issue to remind me of your request.