Ancestral property question

idea can be formed only after seeing the will.

I agree with Sarvanan. It is depend upon the will in which propert ownership described and how your grandfather can distribute his property.

A Will is a legal declaration of the intention of the testator, with respect to his property which he desires to be carried into effect after his death. 

After the death of a person, his property devolves in two ways - according to his Will i.e. testamentary, or according to the respective laws of succession.So grandfather is having rights.on it. 
 

Well advised by experts, I agree.

Now the property in the hands of your gandfather is his self-acquired through the testamentary document of will executed by his father-in-law.

His (your grandfather's) successors shall enjoy the same, if your grandfather has died intestate without disposing of the subject property  .

what was mentioned in the will is the point to consider because in the will if he has montioined only like he can enjoy till his life time or effects thereof absolutely means after his death he can distribute

so will copy is necessary to ascertain what words were written to give correct answer

No mor elaboration required