Create Amazon listing variations for multipacks

Hello,

I'm looking for someone that can create product variations for my products in Amazon. I started selling single units of my products via FBA to get reviews, I now want to start selling as Fulfilled by Vendor.

Now I would like to create 4x pack and 8x pack variations FBV (fulfilled by vendor), ideally retaining the reviews we obtained.

Please do indicate your experience for this specific use case. I would like someone that has done this before.

Best Regards,
Marco