You can buy them as a gift for your sister, you'd be given a voucher you can give her - it would get her in the park the firt time, then she'd need to go to AP processing to actually get her pic taken and get her AP.
Now if you are talking about applying your 1 day tickets or parkhopper tickets to APs for you, then giving them to your sis, that won't work. The Aps would be in your name with your picture.