The person you are with your grandparents and the person you are with your friends should at least recognize each other.

No one is the same in both rooms, and no one should be. The language changes, the volume changes, the subjects change, and that is ordinary politeness rather than fakery. What is worth watching is whether the two versions share anything: the same honesty, the same manners, the same willingness to listen. When they stop recognising each other, one of them is usually a performance you are getting tired of.

Pick one quality you would want in both rooms, something plain like patience or telling the truth. Carry it into the next conversation with each, deliberately. Notice where it gets harder, since that is the room doing the pulling.