I think this is along the correct line, Ichigo and Masaki are perhaps part of his "clan".
I don't think Juha Bach is saying that Ichigo is his own son. He specifically mentioned Ichigo's Mom afterall. If Ichigo's birth parents had been Quincies (Bach + His Mom) then Aizen's statements that Ichigo was part Shinigami and Part human would be completely false.
Bach calling Ichigo "Son" is in the Sense of a Patriach calling one of his Clansmen Son.
^^^THIS THIS THIS.
Finally, I'd like to see Ichigo descend into his inner world and talk to Zangetsu. I wonder now how the Changes Ichigo has experienced , Fullbring, Reiatsu of Captains, Quincy Reiatsu..., how would these have changed the appearance of his innerworld, and of Zangetsu himself.