Board Thread:Off Topic/@comment-26046854-20150126213058/@comment-25555436-20150129163359

Yes, but considering how they are a common target of the WF, the SDC would probably have thought of hiding as many of their members as possible, as making them known would give the WF a new target.

Maybe Winter is hidden, so that if Weiss dies or something the SDC still has an heiress.

Also, it could be that while the high members of the WF knew of most members of the SDC's family tree, it doesn't mean every member of the WF does too. Blake could have been among the members that didn't know the entire SDC family tree and was never told about, probably because her boss(es) thought it didn't matter.