SA cichlids do not readily cross breed if they cross breed at all. To my knowledge there are no cases of festae crossing with anything in an aquarium. So the likely hood that this store bred a dovii and a festae are as close to 0% as you can get. Add in that these fry that are claimed to be crosses look exactly like young mayans and I think you already have your answer.
If they are crosses it is more likely a mayan x dovii cross. That could be possible, however they look like mayans to me.
This is incorrect, Festae has successfully crossed many times in the past with Central American Cichlids. Not nearly as common as it is with Central American but it does happen. It could be safely assumed that Festae is capable of crossing with most, if not all, Central American Cichlids. While Festae is found in South America, it is more or less a Central American.