Create a new listing or add to an existing listing?

I have a successful ebay store, and most of my items are from alibaba. I do not dropship, I ship everything from my own home in the US. I buy in small quantities, check the quality and rate of sales, and then if successful I buy in bulk.

I signed up as an amazon individual seller to see how it is because I’m curious. Most of the items I sell from alibaba have the same item already listed on amazon, but with each seller attaching their name to it. My question is am I allowed to sell using their ASIN, or do I have to create my own listing?