Community Tip - You can change your system assigned username to something more personal in your community settings. X
From what is written in this article it would seem impossible to do what you are asking.
Is it possible to add an object (or object type) to an existing "Subscription" in Windchill PDMLink
Hello KK_8383163,
I confirm this functionality is still not available in 13.0.1.x.
KR,
Charles.