Rights of the first wife and children over father's property

My father ( hindhu rajputh singh from jharkhand ) and mother ( converted christian from SC from Kerala ) has married on 1994 on the presence of 6 witnesess by signing in a letter pad of arya samaj mandir in Noida sector 22.My parents lived together for 15 years ( 12 years in Noida , 3 years in Kerala)as husband and wife and have two children me 22 yrs , and my sister 13 yrs.Father had destroyed or hided that signed letter pad of arya samaj and didn't registered the marriage. Later he went absconding and now heard that he had married ( wether registered or not) another women and have two children in a good status. can we get rights on our fathers property and income? Are we legitimate children ?, can our mother get the dignity and right of first wife ?can we get maintenance according to our fathers present economical status and income ?we have lic policy , esic policy , pan , photos , school certificates, birth certificates etc as proof other than a registered marriage proof .