User blog comment:B214/Talk About What You Want! 3/@comment-24098614-20150329012653/@comment-26268422-20150406224958

Where is it said that Rias has to abdicate or that her children will not be able to inherit the throne?

I've looked and while the prejudice against hybrids is obvious, it is never stated that marrying Issei takes Rias or her children out of the line of succession nor is it ever stated that higher ups would prefer Milicas inherit over Rias or her and Issei's children. Every faction is doing what it can to get children from Issei so it can't be as big a problem as it's being made to be. In fact, now in V.19 Yasaka, the Yokai leader in Kyoto with the huuuuuge talent, asks Issei to wait for her daughter Kunou to grow up. But if he can't wait then she (Yasaka) would have children with him now! So would the Nine-tailed Fox that is responsible for the flow of energy through all of Kyoto intentionally pollute her own bloodline with a lesser race?

Until Ichibumi says otherwise, I have not see anything that would give any credence to the idea that Sirzechs would allow his sister to be put aside, or that the Phoenix clan is ready to write off any grandchildren by Ravel as being sub-par, or that Irina would get special permission and a fall proof room so she can do the deed with him just to produce a "half" and lastly now Yasaka has offered herself and her daughter to have Issei's children.

The idea that any of those groups or characters would settle for a mating that lessened their position or their power is not supported by anything written so far.