Existing tenant wants to add a roommate to lease

[Joe Sauers]

I have a tenant who just moved in a few months ago and has just requested permission to add her co-worker to the lease as a room-mate. I will obviously perform the standard background check that I put any other tenant through. So far the existing tenant has paid on time and not caused any problems what so ever.

My main question is how to handle the lease. Do you guys recommend just creating an addendum to the existing lease, or rather cancel the existing one and write a new one with both tenants names.

Also, how about the security deposit? I currently am holding one month's security plus last month's rent from the original tenant.

I'm open to everyone's opinions, since I have never encountered this situation before.

Thanks in advance.