Regards,
The multi-item return is still an issue with eBay and just so you know, a number of years ago ALL items had to be returned on a multiple item purchase. eBay has historically been good at juggling one ball. Sadly, some of the reason for that is their Seller Metrics and desire to grade sellers on their performance rather then letting them both construct their own deals with Buyers as well as construct custom returns when needed.
In your case and the Seller's if you process all three returns separately AND ship them separately with 3 different labels and tracking numbers the Seller will be charged for 3 return labels (unless you are paying). The return label flow may or may not work right and the thread below is one with a solution whereby a Buyer returned 2 of 3 items in one package with one tracking number ... in this scenario, apparently two labels were generated but one was not used and I surmise NOT charged to the Seller (guess on my part).
https://community.ebay.com/t5/Shipping/Question-about-returning-multiple-items/m-p/30891901#M319158
eBay certainly needs to make the multi-item return more user friendly as well as flexible for what is returned ... hope this helps but I suspect it might cloud the issue for you.
