Yes, you add accelerations as vectors. Say, a centrifugal ring flatly lays on the Moon surface and rotates (around the axis of ring symmetry perpendicular to th

Yes, you add accelerations as vectors. Say, a centrifugal ring flatly lays on the Moon surface and rotates (around the axis of ring symmetry perpendicular to the ring plane) so that the artificial gravity on the centrifuge is about Earth. Moon gravity, about 1.42 m/s^2 , adds perpendicularly to that, so the total gravity is still about the Earth one. The level surface on the centrifuge is slightly tilted away from local vertical, but in essence you just added Moon gravity, vectorally, to the rotational acceleration.