Please can anyone help with Products and Variants?

I started my SnoreMeds shop a few years ago, I have six products with their own SKU and I have marketed them as individual products. URL ( )  I would like to change these products now into 2 products (for men + women) and there be 3 variants of each with their own SKU. However, I would like to keep my existing product pages as they have been indexed and I also have affiliates which market these products. I thought of duplicating 2 of the products and adding the significant variants with it's SKU. The problem I am having is Shiphero  (the fulfillment) sees this as a multiple listing and the inventory is not automatically updated.  Can anyone advise the best way I can implement the change?