can i open ppf account for handicap person?

I want to open ppf account for my sister who is 80% handicaped physically and mentally. I have been appointed her legal guardian by govt of india and certificate for the same have been issued by collector office.
Please let me know if i can open a ppf account on behalf of my handicap sister aged 35 years as her legal guaridan. Note that she can not sign as she is handicap so i will be operating her account throughout.