I believe you will be able to find a way to disable it. DO NOT DISABLE THE DRIVER'S SIDE AIRBAG!!! You said you want to disable both, I'm unsure if you mean both your's and your sister's, or both of your's. The driver's side airbag has saved many more lives than it has takens, just make sure you sit properly and have the steering wheel tilted properly. My mom made me sit in the back till I was 12.

It does suck.