How do you keep your kid from ruining it for other kids?

We don't really have to worry about it this year since our LO is only 7mo, but obviously the holiday has brought up the topic and we're leaning towards telling LO Santa is just a fun make believe thing rather than telling her he's real. But our 2 yo nephew was here this weekend and he believes in Santa and it got me thinking-- if we tell her Santa isn't real, how do we keep her from blabbing to all the other kids? Lol. I mean just bc we're not into it doesn't mean I want to ruin it for other families who are!