Notice for seeking additional information/clarification/documents relating to application of GST num

I'm asked to file A SIGN PROOF of the person who has given CONSENT fur using their property for business purpose.like pan card. but the person happens to be aged not having such SIGN PROOF PAPER. Also documents like aadhar card and voter ID card do not have signatures of the card holder hence they cannot be used here. What other document can i produce to validate this NEW GST REGISTRATION APPLICATION