Questions re: merging existing ASIN’s under a new parent listing

Hello! We are a brand registered company with 4 products in the dog food category that we are interested in combining as children under a parent listing.

I do have a couple questions I was hoping to get some feedback on!

We have existing A+ product description content for each asin that is specific to that asin. Will these carry over? I’d like the customer to see the a+ content specific to each variation when they click through.

Is it best to create a new parent listing or to use one of the existing asin’s as the parent and add the other 3 products as variations to it?

Thanks so much!