It does seem bizarre that a character the bosses didn't want in the cartoon and he decided to write in anyway, is featured (nay, headlines) in the very first episode already:
1. The Abominable Snowbeast
The Smurfs encounter a snow creature that turns out to be friendly with Smurfette.
The description of episode 29 is exactly thesame as the comic:
29. The Smurfette
Gargamel creates Smurfette as a pawn to destroy the Smurfs, and Papa Smurf changes her into a real Smurf to foil Gargamel's plan.
, and also many other early episodes are straight from the comics (AstroSmurf, ...).
24. Romeo And Smurfette
Hefty and Handy, not to mention everyone else, compete for the amourous attention of Smurfette.
Considering that the first year(s) of the Smurfs were constantly supervised by Peyo and Delporte (the original writers of the comics) and that they wanted the Smurf cartoon to be as close to the Smurf comics as possible, I would be surprised if Smurfette, a character which appears in every comic after she is introduced (i.e. in book 3, and we are up to 23 or 24 now), would have been written out of the cartoon originally. The only serious difference I know of is that the Black Smurfs had to become Purple Smurfs for obvious American reasons.