Assigned land as inherited property

My grandfather has purchased a government built house in my village. As my mom was the only daughter to my grandfather it was inherited by my mom after his death . After my moms marriage she was away from the village for a long time and we visited the village every now and then . I was gifted with this property in the form of an agreement at the time of my marriage. As my Inlaws wanted a house there we had built it for them to stay there after demolishing the existing house( which is later home at our old age). Recenlty we wanted to register the land and went to the registration office where in to our shock we came to know that the registration is not possible and our grand father has purchased a SC assigned house .We have been paying property tax from my grandfathers time and the water bill is in my name. We have almost all our neighbours too in the same position. Please help us what to do now . All we have are some agreements passed on from the assigned person to my grand father and my mom to me ( Both grand father and Mom are no more now) Please help.