Newbie landlord questions

[Andrew Heinle]

I am closing on my first property tomorrow (4-plex). I have 2 questions. The tenants did not sign a lease with the previous owner and now are not wanting to sign lease with me. Can i send them an eviction notice without a signed lease?

Also the 1 tenant that did sign wants to add a roommate. What is easiest way to do this? New lease with both the tenants signing or some sort of amendment?