Is GPA without property schedule valid for land sale?

I'm planning to buy land in March 2023 from the current owner, Mr. A, who has possessed the land since 2008. Mr. A purchased this land from Mr. B in 2008 using a General Power of Attorney (GPA). The GPA was registered in Singapore and adjudicated in Tamil Nadu but lacks a property schedule. The GPA includes a clause allowing Mr. B to sell any part of the property. Is this clause valid for selling land? Is the GPA valid despite the absence of a property schedule? Should I proceed with purchasing this land, and are there potential future issues due to the GPA?