Mortagage without possision is valid or not

Dear Sir’s Sub; regarding- facing issues on Inheritance properly distribution. This is about brief on our property details; there was four grandfathers for total 72 acres of land in Telangana (But the property was in the name of only two members out of four, Elder (44 acres) one & Younger (26 acres) one. Supposed to be partition as 18 acres each, equally for all the four members’ of next families. Each on having two sons, means total 8 family members. But in the year of 1989 or 1990 registered all the lands to their 4 families tentatively by the process of mortgage without possession to get the loan from Bank but it was not equally ( some of having 26 acres, 16 acres, 16 acres and 14 acres ). But as per verbal discussion (noted on just white paper no signs) & mutual understanding distributed equally and all are in possession since 25 years, but documents are remains same as registered in the year of 1989 or 1990 and received pattadar passbook also. Now few guys are not ready exchange the land as per possessions and they wanted to be stick on as per pattadar passbook, registered land which in on their names in documents. And in between recently two family guys are exchanged their land accordingly without intimating other two families. Who is had 26 acres given 8 acres extra to the others guys who is had 12 and 14 acres by sale deed. My question is now shall we have rights to fight them to get it as per possessions and register the documents again or not legally. Or the process of mortgage without possession in year 1989 will be considered as final. Waiting for advises. Thanks.