What do you mean with that?
As far as I can tell, a 28th amendment hasn't even been proposed, although there is an urban legend about it that circulates in chain mails.
However...even that fantasy amendment is about equal treatment of citizens and members of congress...not sure how that would apply. The closest I can see is that Holmes's mother was a congressional staffer, but that's (a) not her, but her mother and (b) not an actual member of congress and (c) the laws aren't actually different here(?)
Puzzled.