User blog comment:B214/Volume 23 discussion blog/@comment-172.56.17.58-20170417051436/@comment-29963364-20170418024515

Exactly. That actually helps my point of Rias being "Option A" rather than just a "place-holder" for Millicas.

Befor Millicas was born, Rias was the only option for the Gremory Clan, and therefore the "true heiress" to the Gremory Clan. But after Millicas was born, that was no longer an issue, and she became "Option A" and Millicas became "Option B."

So no. Repopulating pure-blood Devils wasn't the only reason they were ok with Rias' engagement to Riser.

Even when Zeoticas was apologizing to Lord Phenex for the broken engagement, Lord Phenex said "don't worry about it. It's fine, since we both have grand-kids (Ruval Phenex's child, and Millicas)."

So neither one is a "place-holder" for the other. The Title of Clan Head can go to either one, depending on who's older, or who actually wants the position.