You shouldn't re-home them because it is considered to be 'unhealthy' for the tropical fish market. Example, if you sell/donate the fry to a store and the store doesn't know any better, they may resell the fry as "rainbow cichlids" or "Jack Dempsey's" as they will be more marketable and then when they grow up customers will be dissatisfied or downright confused. In addition, customers may then breed these hybrids with other cichlid's and it starts a chain of mixed species fish. Most hobbyists want the pure species and this keeps a natural order. You could argue that CA Cichlids may mate with each other in nature, but I would say that it is a rather rare occasion, otherwise the majority of wild caught fish would be hybrid.
Your aquarium: How big is the aquarium? How big is the rainbow versus the Jack Dempsey?
Two current suggestions if you put them in together:
1. Ensure that there are small caves that only the smaller Cichlid can retreat to.
2. Create many barriers to stop the open view so that the Rainbow can protect the eggs without stressing the JD and this also prevents the JD from scouting around to find the Rainbow to chase from it's 'territory'.
Let us know the aquarium size etc and we can offer more solid advice.
Also, what is your plan for the aquarium long term? What is your ideal setup? These are things to consider while your fish are still growing, introducing any tank mates later on may prove to be difficult. the JD is going to be territorial once it reaches an adult size and you will want to make sure that there isn't just the one semi-aggressive tank mate for it to chase around.