how do I ask without being rude?

I am having a baby shower on Friday and it's going to be at my apartment. I invited my sister-in-law and she has two kids but I don't want them to come because they are sooo hyper! They terrorize my house  and I don't want to feel like I'm babysitting at my baby shower. I have more reasons but I just don't want her kids to come. How do I ask my sister without being rude or offensive? I know that I have other friends bringing their little kids (I'm okay with that but I can't say no kids allowed because of that so how do I ask?