Section 8 Tenant has a question for me

[Meg K.]

My tenant who gets section 8 has informed me that she plans to move at the end of the year (sob sob..she was the best).  She is asking me if I can add her sister's name to the current lease so that she can pass the section 8 voucher to her.  Knowing nothing about the law, i feel as if i could get in trouble for falsifying information.  Anyone has any experience with this?  Also tips to find another GREAT Sec. 8 tenant are welcome :)  Property is in a C neighborhood (last time i went thru over 50 potentials before deciding on one..not looking forward to it).

Thank you!

Meg