New leases or just an addendum?

[Kenneth LaVoie]

I am selling an 11 unit building to an investor in NY who is asking me to manage the building after the sale. My question is, "Can I simply create an addendum for all the tenants to sign that modifies the lease as being between the NEW owner and them or do I really need to create entire new leases?" There are NO lease terms that we're planning to change, ONLY the who the Lessor is.