Cissy Houston -- Hints Family Won't Use Heroic Measures to Save Bobbi Kristina

Pat Houston is now sharing the controls with Bobby Brown on what to do with Bobbi Kristina ... and it appears a rift may be brewing, because a Houston family member strongly indicates she does not want to use heroic measure to save Bobbi.

As TMZ reported ... a judge made Bobby and Pat co-guardians a few days ago, which gives them joint responsibility for Bobbi Kristina's care. As we first reported, Bobbi Kristina is suffering from irreversible brain damage and the prospects of getting better are slim to none, barring a miracle.

Pat says she and Bobby are working as a family to make the right decisions, but there seems to be a clear division. Cissy told "Entertainment Tonight," "She's not gone yet, but you know, whatever the Lord decides, I'm ready for her ... I have nothing to do with that. That's His job."

Bobby, on the other hand, has made it clear he will do whatever it takes to keep his daughter alive, including using heroic measures if she begins to slip away. Some member of the Houston family have strongly indicated they are not inclined to use such measures.

If Bobbi Kristina's condition begins to deteriorate and if Pat and Bobby can't reach an agreement, it will probably be left in the hands of a judge to decide the fate of Whitney Houston's daughter.

The 2 families have been largely at odds since Bobbi Kristina entered the hospital.