Congratulations on your success! I would not recommend breeding birds that are in any way related. And here is the long explanation. Both the “Yellow-Sided” and the “Pineapple” conure are color mutations of the Green-Cheeked conure. So they are not separate species. This also explains why you ended up with the “Pineapple”. With color mutations, traditionally a name for the mutation is assigned, but the species of bird is always part of the name. People have shortened the mutation names for the Green-Cheeked conures, to only have the mutation. So the correct term would be Yellow-Sided Green-Cheeked Conure and Pineapple Green-Cheeked conure. Think of it like Cockatiels, where you have Lutino Cockatiels, Pearl Cockatiels, Pied Cockatiels, etc. Any time you are dealing with color mutations, there is a genetics chart that will tell you which percentage of chicks will be a certain color mutation. So you could end up with other mutations than the Yellow-Sided and Pineapple in the future. Unfortunately, the genetics charts are not only really confusing, but they are only accurate if you know the background of the birds all the way back to the original Green-Cheek parents they came from. Color mutations are actually a genetic flaw. This flaw in the code affects the colors. A flaw like this can occur in any bird or mammal species. In most cases it is too rare to try to breed the animal to get more with the same flaw – or mutation. But with a smaller, more prolific species like the Green-Cheek, the mutation could be bred, and eventually new mutations could be created, just as with Cockatiel, parakeets, lovebirds finches and many other small bird species. The problem with the Green-Cheek mutations is much like that of any popular pet, where volume breeders allow related birds to breed and many of the birds out there have genetic weaknesses because of so much inbreeding. Since you have no way of knowing if yours came from related birds – and most likely they did at some point down the line – it’s better not to keep that going. You could end up with weak, sickly birds. The best thing to do is find a breeder who is willing to trade unrelated birds so you can get some new genes in your line.
Thank you for asking Lafeber,