relative died without a will to his property, but the sister is now paying the mortgage and doing the management&maintenance is it possible to turn the property over to her name.

only if they left it to you greedy

who did he leave it to in the will. if not the govt will decide usually it will go to next of kin

There needs to be a death certificate, hopefully there is a will leaving it to her otherwise there could be some work to deal with that. She would need to take it to the property holder (who she makes her payments to) and talk to them about switching the names.

She would need to consult a solicitor and keep all the receipts she has outlayed toward the upkeep. There is a good chance there are other relatives who would be entitled to a claim so it would need to sold and divided up. If she went ahead on her own, she could be charged with fraudulently obtaining property without consent.

The correct procedure is to apply at a court for probate. If there is no will, then the law of the land will specify how the estate should be distributed to the surviving next of kin. There could be costs involved to place advertisements in the local and national newspapers as required by law. A solicitor should be engaged to take care of these matters.