Transfering rights of Property

Dear Sir, I lost my father about a year ago. My brother is an NRIs and I stay in Mumbai. The asset in India is in joint names between my mother and father. I just found out that according to the law, my mother still inherits only 50% and my dads shares are now split between his children (me and my brother). Is this true? What exactly do we have to do next? Should we get a succession certificate or legal heir certificate? What is the exact process and an estimated timeline? For this process, do all the inheritors have to be there to obtain these certificates or can my mother alone obtain what is necessary. Additionally, does each asset have a separate certificate or is it one for all assets? Lastly, I am currently residing outside the country and traveling is very difficult for me. Hence I would like to give a POA to my mother for the assets. Is that possible to do so? what is the detailed procedure to obtain POA? Can I sign the POA outside the country? Or can the paperwork be started without my presence in India and then I can come to sign the papers?