My sister-in-law wants my husband to give her away (they are very close). Their father will be at the ceremony too. Their relationship with their father has never been close, far from it. Aside from dads feelings (possibly being hurt) are there etiquette reasons that dictate my husband can't give his sister away?
No, anyone can escort her. As you point out, this could hurt the father. Many fathers think of this moment for many years. But, if they are not close, this may not be a surprise.