Gpa clause in sale deed

To correct this omission, the proper legal step is a Rectification Deed.

Executed between the same parties as the original Sale Deed (i.e., the Seller and the Buyer/your sister as GPA holder).

Registered in the same Sub-Registrar Office where the original sale deed was registered.

The purpose is to correct the recital and clarify representation—that your sister executed the deed as your GPA holder.

Rectification Deed for clerical or recital corrections attracts nominal stamp duty (usually ₹100 or ₹200 + registration charges).

If it doesn’t alter consideration or property extent, no additional stamp duty on the property value is needed.

Thanks for the response. 

Is it normally a problem not to have the GPA clause in the sale deed and have the GPA holder sign all the pages of sale deed? 

You purchased the property, and the sale deed in your favour does not require a GPA except for a representation form.  For mortgage purposes (to take a loan), you have to give your GPA to your sister, as you are abroad.  The GPA should be attested by a Notary Public or a Consulate abroad.