there are no rights or wrongs here mate many roads lead to Rome and all of that lol im not a great believer in close inbreeding all of the time a cross mate should put some vigour in your young birds also might be a idea to split the good pair so you have half brothers and sisters also it might be surprised to find its one of the stock pair that throwing the goods if so u are in a lot better position than having a pair that only breeds when they are together probably the best book ever written on starting a family is the masters of breeding and racing by van salen (spelling) very hard to get your hands on and very expensive but you may know some one that will lend it you too