I think I got it figured out. Mr. Burke lives in a hotel. The MC's grandpa owns hotels. The MC's mom was a Burke. It all fits. Jade is married in, so no blood relation. Sage is adopted. So no blood relation. It all makes sense now.
Promising speculation, but there is an elementary detail you've over looked, my dear Talmadge. Excuse me a moment as I put on my deerstalker and light my pipe.
Now then, MC's grandparents sold their home to the Royces for financial reasons, yet Stephen Burke is a very wealthy man. This does not quite fit.
However, it is reasonable to assume that the families knew each other through their manoeuvrings in the financial circles.
So, the idea you have inspired for me is that young Stephen Burke wanted to marry Lynette, but got cucked by Neil Miller. The marriage of Stephen and Jade is falling apart because Stephen settled for something he could get and never actually cared if it worked or not.
Now history is repeating itself as a Burke wanting to marry a girl who grew up in that house is again cucked by a Miller.
And Tybalt actually is a Burke by blood. It's just that Stephen is the only one who knows this. Tybalt's biological mother threatened to ruin Stephen's reputation, but he paid her off and took the boy in. Stephen feels like he is raising someone else's children because he is a sociopath.
And there is your cue to say: "Brilliant, Roger!"