1 year Tourist Visa for niece

iheartau

hello!
My husband and I plan to file a 1 year tourist visa for my parents-in-law coz we're having our first baby - this is just straightforward TV application. But, we want our niece to come with them, since she's been living with them in the Phils.. She's 8 years old and we just plan for her to stop school for a year. Do you have any ideas if this will be approved?
And, another question, if we apply for their tourist visa in one application, if one is denied, will all be denied? Is the approval/denial per application or per individual?
Thanks.