Wonder Lister
User guide

How do I copy my existing listings from one eBay account to another?

Since eBay does not allow you to edit your existing listings to change the eBay account used, thus revising existing listings is out of question. What you need to do is as follows:
Bulk Duplicate listings of old account. The duplicated listings will appear in the Grid
Select them all in the Grid, then do Bulk Edit using the option "Edit / Revise Options" > "Bulk Edit"
On the Bulk Edit window, change the account to NEW account
Also change the profiles (payment, shipping and return policy) that belong to the NEW account
Save the changes made
Submit these duplicated listings
You may want to END your ACTIVE listings belonging to OLD account.