How to be legally sound on plots my grandfather left (No Will)..?

Hello Sir/Madam I found this forum while searching on Google. I am from Punjab. My grandmother and grandfather died 1.5-2 years back. My father has 2 sisters and 1 brother. All in all they are 4 brothers-sisters. Our grandfather and grandmother have lived with us all their life. Now, some properties are in my father's name already but many of them are in my grandfather's name. My mother tells me that the properties which are in name of grandfather have been mutually discussed among 4 brother sisters and mutually agreed on some paper share wise. I live in Delhi. My mother is asking me to arrive home and legally get all properties due to us on names of my father. My father is old age and ill and hence, cannot get all works done. I need some guidance on how to proceed, how to start and make sure all steps I take make my family legally sound in respect to these properties. We are afraid because 10 days back, my father's sisters came to our home for 10-15 days (they never stay for so long). We smell something fishy going on. My father is not very knowledgeable and can be easily fooled emotionally. Also, there was one land on my grandfather's name which was given to us (on my father's name) but when we visited, we saw a home already built by some one there. We are very sure that my father's elder brother has done something fishy there. Hence, before its too late,I want to make sure me and my family are legally sound on all these properties. I hope I can get some good advice to begin with. Would be great if some lawyer can contact me via phone as well. Appreciate you in advance. Regards