Question
Some time back I wrote grousing about eBay cross promotions being put in place such that we all automatically participate in them. This is where your auction is used to promote your competitor's goods. And their ads your goods conversely. For some of us, this is a bad idea. If we sell the same items repeatedly, giving someone access to put their "cheaper better" in front of your customer's eyes in your ad just isn't great. And if we sell antiques for example and have two of the same but sell them one at a time, then having a competitor put their items in front of your bidders isn't wonderful.
At that time, I turned off their cross promotions. And then I went back and checked and hello - they were back turned ON. I had to set them to NO twice to get them to stay that way.
So I was particularly unamused to see that cross promotions are back to YES on my account. I have again set them to NO. And this is months later that they had changed to yes.
I suggest checking YOUR settings.
Answer
I believe you can elect to cross reference with other buyers though that are will to cross reference back with you. I recently did this with our sister store and seems ok so far.