My question involves landlord-tenant law in the State of Indiana

My sister moved in with my fiance and I at the beginning of September because she'd lost her job and said she didn't have anywhere else to stay. We let her live with us without paying any bills because we wanted to help her get back on her feet, get a job, and save her money for her own apartment. In October she started staying somewhere else. She only came by for a few minutes 3 times to get some clothes. She left our spare bedroom trashed. since she'd moved out we had a friend who needed a place to stay for awhile and had agreed to pay rent we tried to contact her. Both my fiance and I texted and called her multiple times and he sent her a message on Facebook about it. his message showed up that she'd read it and she blocked both of us, and still didn't respond. She wouldn't reply to me when I told her I needed my house key back, so we changed the locks to make sure we'd be present when she came to get her belongings. We waited 30 days then boxed her things up and donated them to goodwill as we believed she would no longer be coming back to get them. Our friend moved in last week and has already paid rent, but today she tried to let herself in our apartment, knowing we were at work, with the old key and couldn't get in. she then showed up at my work demanding my key to get her things. I told her we'd given her things to goodwill after 30 days as we tried over and over to contact her and she wouldn't respond. Now she's threatening to take us to court saying she never received any of our communications even though we both still have proof. I would like to know if she has any grounds for this as it was her choice to move out and she knowingly left her things and refused to respond to any communication from us.