Create variation listing from existing listing

Hi all

I’ve been struggling with the process of creating a variation listing so coming for some help!

Background:
To date I have tried using the inventory upload file to create a new parent SKU and associate my two EXISTING child SKU’s to it, so on Amazon customers can see two pack size variations but IMPORTANTLY I retain all my reviews and customer questions on the child listings. I keep getting errors using the upload file and then when I finally got it to work it deleted my two existing ASINs and put them in stranded inventory. Mild panic over I realised that all reviews are linked to the ASIN so I just created the listings again and I was back to where I was before I started! Still no closer to creating a variation listing!

Question
Amazon Seller Central keep advising me to use the inventory file process but I’m obviously worried about doing this again!

Is it an option for me to do the following and if yes any thing I should watch out for?

1. Add new product using the manual process in Seller Central Inventory
2. Select 'Product not sold on Amazon
3. Go straight to variation tab without filling in any product info e.g. EAN, SKU etc
4. Add 2 variations and use my existing SKU and Product ID codes

If I do the above and save it, will it create a variation listing with my existing two ASINs, retaining all my product reviews, customer questions, ranking etc ?

Thanks in advance