Ah, we have a rule that our legacies have a have a few generations between godly ancestors, otherwise they could be too powerful. In the case of my Praetor Primus, for example, his parents are a legacy and a demigod. This is perfectly acceptable. However, having Ceres hook up with a demigod is against our rules. Think of it in the sense of Frank. He's a demigod and his mom is a legacy, but there were multiple generations between Frank and his original Neptune demigod ancestor. If you want your legacy to also be a demigod, you should have quite a few (at least four or five) generations between them and their godly ancestor.