Maybe talk to you sister and see if she can "buy" it from you as is ~ so that she can view the "damage" that she has caused?? I buy gifts for my sister all the time, gift is a gift... Although my sisters and I never borrow things from each other (we are very different in terms of "styles") however, IMO when it comes to "borrowing", then there should be a rule like "if you damage it you pay for it" kinda rule? Regardless sisters or friends... we should be responsible..... no hard feelings