Sister=Crazy?

Ok, so I am 16 and my sister is 17, yet I think that she is crazy. Here’s why… Basically, my mom dated this guy three or four years ago who had a son that was 7 years older than my sister. well, when my mom and her boyfriend broke up, my sister started telling people weird lies. they’ve varied as the years have went on, but they all have the basics of her being married to this guy and having his children and them having their own house and him being in a band. she always tells her friends that she’s pregnant and then when it comes to the time that she would be “showing” she decides to tell them that she had a miscarriage. yet, as dumb as this all sounds HER FRIENDS BELIEVE HER!! my mom finally put her in counseling about 3 or 4 months ago, but they dont ever even talk to her about that stuff…which is kind of weird. she also likes to get up at about one or two in the morning and go to her room to play with her baby dolls and act like they woke her up hungry and stuff and she’ll sometimes play with those bratz dolls things…it’s kind of weird. I’m so scared for her because she is like my little sister to me…not my big sister. and I’m afraid that the wrong one of her friends is going to find out about her lying and is going to be pi$$ed. any advice on what to do about it???

PLEASE HELP