Well we know Allana is going to be trained as a Jedi. At least at the end of FOTJ and she will likely become queen of Hapes. And she is ten at the end of FOTJ. So assuming she spends 10 to 15 years as a Jedi and reaches Knighthood by the time she is 30. She will be under constant supervision until then. Assuming she becomes Queen upon her mother's death, retirement, or political resignation-probably another decade or two-she'd be in her forties or late thirties. A child had at this point(say with a lover while as a Jedi apprentice) would be possible I suppose. Though of interest to the Hapans. Anyway Allana's trajectory in life doesn't lead well to having secret love childs-after all she is the Jedi Queen Jacen foresaw the holding the balance on the white throne. Such a woman probably would have a busy enough life.