If your father had purchased the property by a registered document, his sister cannot name transfer the property to her name without getting it registered on her name.
You must file an objection with the authorities stating that she has lied by creating fabricated documents for wrongful gains and thus have got th property transferred to her name.
You must prove that your father was married and yo are his daughter.
Hence the transfer of property fraudulently made by your father's sister to her name is illegal and invalid and not binding on you if your father has died intestate.
You can file a mandatory injunction suit against her and also can seek possession of property from her since you are one of the actual legal heirs of your father.
You can also lodge a police complaint agaisnt your paternal aunt for her this fraudulent and cheating act.