[Sleepy Speculator]

Why not go one step further and have them actually be Miya's children, she's not technically a sekirei. If Takehito and Miya had offspring, would they not technically be an example of very strong human/ashikabi? First generation ashikabi if you will.

Would explain why Takehito had to dissapear in some sort of argument with MBI. And Miya would endanger the existence of her own children, hence the deal with Takami. Only thing is until it's revealed this is all pure spec, with no proof.