Robkelk explained that AKAs are redirects which helped me with P&C
If I understand what you're asking, that's called a redirect. Start a brand new blank page named after the alternate name, and type in #REDIRECT[[name]], replacing "name" with the name of the existing page, then save it off with only that text in the page.
But only do this when there actually are two different names for a trope or a work! If there's only one name, it's better to rename the existing page.
I see. Well, in this case, "Pepper&Carrot" is the One True Name; I moved Pepper & Carrot to Pepper&Carrot and category:Pepper & Carrot to category:Pepper&Carrot, leaving redirects at the old pages (which I see have been deleted, which seems for the best) for that reason. In contexts where an ampersand can't be printed or urlencoded, such as the comic's domain name or PMwiki's naming scheme, the & is either simply omitted or replaced with " and "; but this is not really an alternate name, just a technical matter of presentation. So if on Mediawiki-based tropes wikis such as ATT (Miraheze), ATT (Fandom) or TTW (Fandom) which can support the full name in their addresses, the redirects serve as true alternate names (not error-correctors/-collectors) then I'll leave it as is. Thanks.