I think Mariah will not tell Sharon unless she has to b/c she does not want to be the one to deliver heart breaking news to her. If it's just a kiss or two, there is a chance Scott will realize he does not want to risk the possibility of real love & a family (which he has never really had) with Sharon just for a bit of tickle & bounce with Abby. If she sees signs that there is more going on, I think she WILL tell Sharon even though Sharon may hate her for it (for a while). Meanwhile, Faith may not be able to keep quiet. And, alas, I DO think Sharon needs to know. How will she feel when she finds out two of the people she loves best in the world, her daughters, both knew Scott was a cheater & kept the secret from her? She will feel that they all three have betrayed her & allowed her to look like a fool. On the other hand, there is the "shoot the messenger" syndrome in which she will not believe them if they tell her.