I'm going to tell my sister to pull herself together after our grandfathers death
Why would you tell her to pull herself together?
She's making the whole family cry.
Your sister is fully upset over someone she was close to in her family, but to tell her to pull herself together seems very harsh. Understand where she is coming from, take her feelings to heart. It takes time, and slowly but surely she will get over it more and more but not by force.
I think she's just being miserable.
It just sounds like she really cared about your grandfather and you should give her the time she needs to grieve.