Gotta say, it’s sorta funny to think that no matter what sort of Universal Monsters house they do, it would be easy to cleanly create a through-line to Epic even if the designs and storylines are COMPLETELY different.
Isn’t the plot of Epic’s big ride that a descendant of Dr. Frankenstein has resurrected some of these characters? If, say, this season’s Classic Monster theme is “Battle Royale”, where they all end up dying in the end and wrapping the series up, wouldn’t it be extremely easy to imply a time jump “Case Files: Unearthed” style which shows Victoria Frankenstein discovering the castle and thus setting into motion the events of the park?
Even if this is described in a… like, a comic book prequel, you could draw a pretty clear line if the characters are meant to be redesigned by Victoria anyway.