Simply put...you can't make a dog love you or even like you for that matter. If they haven't bonded yet then what she is doing won't make things any better. I have 2 males and they are totally different, Jo is independant and will come to me when
he wants to, Riley is part velcro! Don't get me wrong, Jo loves to snuggle and be carried around but it's when he wants to and not neccessarily when I want to...as long as he can see what I'm doing he's fine. Riley, on the other hand, is so attached to me that sometimes he gets in the way. I can't do anything without him right next to me or on me. I can't use the restroom without opening the door and him practically falling in the room, he lays on the rug when I cook, he helps me unload the dishwasher, put groceries away..everything I do he's there...he lays against me when I go to sleep and wakes me (at sunrise) in the morning. Jo prefers to sleep in, at least until 7. They all have different personalities... some are clingy and some aren't but that doesn't mean they don't love you. Now, if I could only combine the 2 personalities, a little more here...a little less there...it would make the perfect dog
Maybe your sister's Yorkie is more independant like Jo.