Any landlord could appoint or direct any person--family member, boyfriend, outside contractor, friend, employee--to manage the property and/or deal with tenants on his/her behalf. The person named to do this does not have to be on the lease. You should request written confirmation directly from the landlord that the boyfriend is now acting on her behalf; until you get same, continue to deal with the landlord, to make sure this isn't the boyfriend for some reason, good or ill, taking this upon himself without authority. Once you get written confirmation, however, you should deal with whomever the landlord directs, while making sure to document everything to do, send, and say.