In case anyone missed it, Grandfathers are predecessors of their offspring. Can't Grandfather anything in that didn't exist at the time the rule was made.
A new term would certainly be in order here.
However, this loose interpretation of Class rules and definition is a losing strategy for F-16 class growth. Formula classes are only successful if the participating boats use the formula. If you don't abide by the rules of manufacture, you should NOT be allowed to participate in the Class events other than sharing a start line or race course.
I have no prob with friendly scoring of Sloop Uni competitors who adjust their sail plan to make use of the classes versatility, Maybe even allowing the A-Cats to race with us on an equal handicap rating, but when it comes to who wins a trophy for an F-16 5 boat+ class event, It is not wise to allow your trophy to be given to either an ACat or the New Cirrus Evolution, or any other boat that doesn't meet specs. Sounds like we could race Hobie 17Sport with a Kite and hang with the F-16 Guys. Or the same with a H-14 with the F-16 sailplan! Too many exceptions will destroy the class, or keep it from ever taking off.
You have to decide whether you want a Formula class or just a bunch of similar boats racing.