All the above, and just to add, although there is not an express policy re: linking to another ID, there is one that says if you have more than one ID, they are not allowed to interact with each other in any way, and (anecdotally) I believe sellers have been advised by eBay reps that it is against the links policy.

Even though many of eBay's policies are written in a way that they don't answer all questions or scenarios, and are also a touch ambiguous, plus the fact that eBay reps aren't exactly famous for being well versed in all of eBay's intricacies, I'd personally err on the side of caution and not include any links.