I-130 petition for relatives

Hello, I really need some help please. It’s my first time submitting I-130 for my married sister. I thought once her I-130 is approved, her husband and children are automatically be part of that I-130 ad all of them will be able to get here. Am I wrong? Do I need to submit a separate I-130 for her husband and each of her children? That would would cost me an additional $1,605 and that is a lot of money.