All three cats are now eating together. Kiera the 17 year old matriarch, Natasha the 10 year old experienced one with clout, and Felix the one year old clobbering overgrown kitten, all eating off the same thing.
Had a bit of a problem earlier as the bowls we had weren't big enough for three cats to eat at one time. Actually they were only big enough for one cat mouth really, as Kiera and Natasha would eat together but have to take turns sticking their nose into the bowl. It was quite cute. In the end I tried just a big plastic lid and there's enough clearance around it for all three cats.
Looks like Felix, although he's an annoying clobbering shit sometimes, has been accepted.