I am a retired US Treasury enrolled agent and a retired Master Tax Advisor for H&R Block. My advice is for you to go get a CPA or enrolled agent to advise you on this. You could be setting yourself up for a big tax bill when you sell this property if you don't get YOUR BASIS (cost, sort of) in this property establish before you roll along with all these changes like renting and rehabbing and expensing and buying out relatives.
You may have already "sold" it as an heir when you bought your sister's half.
Also, you need to learn about being considered "in the real estate" business so that you can AVOID being treated as a passive investor in this property if at all possible.
I can guarantee you one thing. You will be glad you followed my advise. It "costs" a lot of tax money to earn rent as a passive investor.
