Can I send application for parents in the same envelope?

Hi

My parents are above 60 yrs and I am applying for their visa thru drop box.. I was wondering if I can send both the applications in the same envelope with one set of documents or I will require two sets of documents like affidavit of support etc for each of them..

thanks

Raj

just 1 set of documents.
Application form and Fee should be separte for both of them though.