She obviously feels safe and loved. You mentioned you hear doors close. I take it she not an angry spirit. It's also possible that you two knew each other in previous life. Or perhaps, when she was alive she wished she lived with your family or that you were her big sister. Now that she's in spirit, she can have her wish. Unfortunately, her version is a pale imitation and nothing like the joy she'll know when she finally crosses over.
I seem to remember that smudging might help clear the house. But I don't know if that would send her into the light or just send her somewhere else to remain earthbound. the folks on Doreen's site can answer that one too.