If your FIL is the title holder of the land /plot/house built on land then your FIL can dispose IT in his lifetime by a valid/registered deed say registered Gift Deed in anyone’s favor e.g; his daughter, son in law or even stranger……..
The stamp duty, charges are state subject and might be even available on website of Registering Authority/concerned Dept…….and might be NIL/reduced/negligible in case of blood relatives/relatives/relations…
Look into list of blood relatives/relatives/relations…..and charges accordingly…
Or inquire in person in jurisdictional O/o SRO…
Or check with any senior deedwriter near jurisdictional O/o SRO…
Or ask your own very able senior LOCAL counsel of unshakable repute and integrity specializing in such/revenue/civil matters and having successful track record in such matters…..
While daughter may be covered, son in law may not be covered for waiver.
Although you have mentioned that property is not ancestral, and probably FIL has invested from his self earned/acquired funds/estate to acquire said land plot, still IT shall be appropriate to show mutation records with all link docs to your own counsel and confirm nature of property and proof of source of funds. Your counsel can also help to draft suitable deed to mind future interest.