Health insurance for father

Sir We are four in my family me my sister father and mother.We took health insurance for our mother individially(during that time we didn't know to join father)Now  we tried to make it joint by adding my father also,My father is 71 years now so they told they cannot add . 1) DO u suggest any good health insurance for him. 2)Is it  better to get senior citizen health insurance individually for him or family floater which covers me and my sister .Which is better ? (Some insurance people told will not cover me and my sister if we take in his name as we are more than 21 years) 3)Is it good to take health insurance in my name which covers both my parents n me 4)What things to look in to before going to health insurance do we have to go for only governent insurance or private? 5)could you suggest combination of health insurance n top up plans we can go?