Gift settlement deed

Sir, Let me give short brief. As my dad , aged 75 years and recently (3 months before) diagnosed with heart attack. Angio plasty did for him and now recovering .In the discharge summary cardio specialist reported the complaint of memory loss (psychiatrist adviced before angio). All the surgery expenses taken care by me the second son till the first review of him and later taken back to my sister's house to take proper care as i am working in abroad and my elder brother wont take much care. After 10 days my dad used to mobilise and went for his shop where my elder brother used to do business as goldsmith. my Brother took him to registration office and made gift settlement deed of his 4 properties in his name. After a month while returning from abroad came to know the instance from my uncle and requested the document from registration office and it was true. For your clear understanding all the properties bought my dad not by his own money as we all stayed together even my elder sisters (3 members) contributed . My mom is no more in early stage of mine and my brother is staying with his family along with my dad. Initially i am working outside my home town and used to come home before my marriage and after my marriage often. When i enquired to my dad about the gift settlement and he is unaware of this. When i contacted the Sub registrar office , the representative cleared me that SRO not have the rights to cancel the Gift settlement and only option is to go by Legal. As my dad is not in good position (discharge summary of Doctor is with me) to offer the gift settlement to my elder brother, secondly all the propeties are not earned only by my dad as every body in the family contributed, finally after the settlement completed whenever dad approaches to his home, my brother took him and dropped him to my sister's home and reluctant to take care of him. (kindly note i used to send money to my dad since from my employment, did all medical expenses surgery (neuro surgery at CMC hospital vellore, Cataract operation for both eye and recently angio surgery at salem Tamil nadu). Have the proof of money spend as i used to send money thro online and recent operation used card swipe. Can you advice /suggest me how to revoke the gift settlement . My wish is to share the property to all the family members.