I don't want my sister to have any more kids
Why do you not want her to have kids?
Babies will cry all of the time.
You seem to dislike babies because they cry, but you were once a baby who cried also. You are an adult, put up with the crying, diaper changing and everything else a baby needs care with. You should really care about the welfare of the baby rather than your own with how they cry and annoy you.
I wish they were never born.
If your sister wants to have a baby, then that is her choice. You cannot and should not try to influence her, you need to deal with it.