Here is what I did when I sold multiple plants from the same ad: When the sale was done, I simply clicked on the link that said 'Post identical item'. I did that as many times as I needed to so that I could leave feedback for everyone I sold to. It worked well.
One problem I had was that when I edited an ad, it wiped out all the questions and answers that were with that ad. It was like starting all over again. I almost panicked because I didn't know how to get hold of the person who had questioned me about the plant. Fortunately they contacted me and it all worked out.
