Well the surefire way of preventing the parents from eating the fries is by separating them to a different tank when they hatch, or even as eggs (though in that case you'll need to properly filter the water and keep a careful flow over the eggs to keep them from being covered by fungi).
Keeping fries in a separate tank, I've been told that you should make regularly water changes to reduce the amount of suppressive hormones in the water and hence promote growth. However doing too many water changes can cause a too sudden change in the water parameters and kill off the fries, which are susceptible to quick changes at that stage.
Here's my personal experience with taking care of my hybrids - I had an Ellioti and Convict breed, and I removed the parents just as the fries hatched (thought the eggs were eaten, didn't know they hatched as otherwise I'd leave the momma in - momma is a Convict and they take great care of fries):
Initially, they'll be wrigglers in the sand that will feed off their eggsac, but that'll diminish quite quickly. A parent cichlid would search for food and crush them up and spit it out for the fries to eat at this stage, but since the parents were not there, I actually took sinking pellets in between my fingers and actually place them in the middle of the wrigglers (they will tend to huddle together). Many of the fries will develop much quicker than their siblings, and so they'll need non-eggsac sustenance very soon after they hatch.
Once they start to jump around the tank, I start crushing up the sinking pellets and sprinkle 'em all over the tank to fall evenly all over the tank for the jumpers to have a chance of eating something. I also do keep my tank slightly 'dirty' and I turned off the filters when I found the wrigglers, so stuff do grow all over the place and they can forage for their own food if they can't find what I provide.
Anyways this stage won't last long and soon enough they'll be swimming all over. Here it's simply, just crush up any fish food and sprinkle it all over the tank.
At the moment they're 16 days old and are doing well - I had about 150-200 fries, about 5-6 have died so I'm hopefully.
What I stated could work for you, or might fail miserably. I recommend having more experienced breeders come by and give their suggestions. My above account is actually my first time breeding cichlids (I have never, ever bred cichlids before) so I'm sure many things can be done better, but hey they're surviving, so

.