Parents who don't do Santa, what do you tell your kids to keep them from telling their friends the truth?

A bit of background first. My daughter is half-Jewish, and I myself am an ex-Catholic. My daughter is almost 2 and we have decided that we are not doing Santa Claus. We will be doing low-key, secular celebrations for both Hannukuh and Christmas and we have figured out a fun substitution for Santa so she won't be feeling "left out." What do you tell your children to keep them from spoiling Santa Claus for others? How do you explain to them that some children really believe in Santa? I'm a bit worried she may spoil it for others (...like I did as a child and I still feel guilt for it). Thanks for any advice! via /r/Parenting http://ift.tt/2iEhpln