Property Card Mutation

There are few basic points of this matter. 1. My friend's father died with will for a flat in Vadodara. 2. We are not able to fetch any sale deed or any other related documents which can help us to prove that his father is owner. 3. We approached builder in this context he said he don't have any documents as he sold this flat 30 years ago. And he never missed any sale deed. So there is no point in making duplicate or another sale deed of same flat. It's illegal. 4. We are still trying to fetch any copy of sale deed from local sub-registrar office. 5. In mean time we applied for probate certificate in Civi Court requesting her mother as lawful owner of said flat. 6. Honorable Court grant us probate stating his mother as lawful owner of said flat. 7. We applied with city survey office for mutation of her name on the basics of probate order. 8. City survey office is in confusion about this mutation as his father's name is missing from earlier record or sequential record of said flat. 9. We have said that her ownership is granted by superior authority which you can't deny. Questions 1. Are we on right track? 2. Can we get her name on land record by the way of probate? 3. What legal ad is available in this case if City Survey office deny or application for mutation of her name in property card?