Forced Baptism?

My parents are trying to force my brother and sister to be baptized. (I'm not because I'm over 18) My mother and father have recently converted to catholicism, but my siblings and I have remained agnostic/atheistic. They are both over 13 and are against the baptism on the grounds that they do not believe in christ and it goes against their beliefs. Do my parents have the right within the church to force them to be baptized? What can my siblings do to fight this? What should we say when arguing against it? Thanks for your time.