How can I move child variations to a new parent?

I have 1 parent listing with 43 variations that I would like to split into 3 parents. The variations include different sizes, thicknesses and quantities of paper but Amazon has changed the format recently so the listing is looking very confusing!

I would like to split the current parent listing up into 3 parent listings – 1 for A6 size, 1 for A5 size and 1 for A4 size and then within these 3 listings, I would like the variations for sheet quantity and thickness.

Can anyone tell me how to do this please while still maintaining the original 43 child listings/variations so that the feedback still applies to them?