We broke the story ... TJ -- Tito's 34-year-old married son -- has been acting like a quasi-parent to Paris, Prince, and Blanket.
TJ is basing his bid on the fact that Katherine Jackson has been MIA and not providing proper supervision of the kids.
As we reported, Michael's three kids all love TJ and want him to become their temporary guardian.
In addition, lawyers for the Michael Jackson estate are in court and will support TJ's bid to become temporary guardian.
We're told Katherine's lawyers will also be appearing in court to provide specific never-before-heard details about Katherine's disappearance ... details that will affect TJ's bid for guardianship.
9:35 AM PT -- TJ has just arrived at the courthouse along with an army of lawyers -- his lawyer, the kids' lawyer, lawyers for the MJ estate, and lawyers for Katherine. Talk about one expensive hearing.