In order to use multiple eBay accounts separately without logging on and off every time, you can create a new chrome browser user for every additional eBay account.

Click on your user and then "Manage people":

Then click "Add person":

Give it a name and click save.

Now download the SmartyDrop extension in this new Chrome user.

Sign into your Amazon and eBay accounts.

Then sign in to your SmartyDrop account.

From now all you will have to do to switch between accounts is click on your user icon and choose the other eBay account you would like to manage.