are the appliances legally theirs? if so, they go back, no matter how inconvenient for someone else.
why would it be inconvenient for the new tenants? if they have to go back, give the new tenants notice you're coming in and go with the old tenants at a set appt. time to remove them ... no need for the new people to be there.
if the appliances are legally the old tenants, why do the new tenants have access to them?
If these appliances legally belong to the old tenants, AGAIN, why did you move someone in without removing the appliances first?