To do this, you should keep your new cat in the safe room with the door closed, and your first cat on the other side of the door with his food dish. (oliveshope.org)
I used a 2 × 6 on the right side of the door frame to give extra support for my old barn door. (grandmashousediy.com)
Once your cats are on opposite sides of the door eating comfortably you can open the door a pinch so they can see each other while eating. (ivghospitals.com)