Hello Art,

Hope you are doing well.

In odoo when a new always(instant) attribute's value is added then variant for all possible combinations are automatically created. To create a single varient you might need to override odoo's methods but it will be much difficult as lots of odoo default flows will break.

ie: In website sale / shop the other possible combinations will not be available apart from the one that you created which will give combination does not exist error.

There is an option for dynamic in Attribute and such variants are only created when you add the related combination in sale order.

you can check how odoo manages dynamic variant creation and create a custom method which manages creation of single variant based on provided combinations and trigger it from xmlrpc.

I think you should use dynamic attributes instead of instant for single variant creation.

Thanks & Regards,

Email: odoo@aktivsoftware.com

Skype: kalpeshmaheshwari