It is not clear where Keiju KYUAN came from, but it is possible that Nobutada's real mother came from among the family of his close advisers considering the fact that families of birth mothers served as close advisors to busho such as the Ikoma family serving Nobukatsu and the Saka family and the Okamoto family serving Nobutaka.
久庵慶珠の出自は不明であるが、信雄には生駒家、信孝には坂家、岡本家というように、生母の一族を側近につけられているので、信忠の側近の中に信忠の生母の実家の一族のものがいる可能性もある。