Which sentence is correct?
To say: My house is your house.
Is it Mi casa es su casa or mi casa es tu casa?
EIther one is correct-it all depends on how close your are to the people you are welcoming into your house. If they are close friends or relativews use tu. What I mean is, sometimes one has people come over the house and one has not developed a close relationship.Back in the days (50) in Guatemala "usted " was how you referred to people you were not very close,like your boss or someone in authority. "tu" was used with relatives and "vos" was used with your buddies.
The best advice or my best advise is, use what ever term "usted,tu" you are most comfotable with.
I think that either is correct, but given the sentiment of the statement, it is probably better to say "tu."