Sources connected with the Singleton family tell TMZ ... Shelia Ward is not only up against John's daughter, Cleopatra ... but also his current girlfriend, and his estranged father.

As we reported, Cleopatra filed a motion last week, attempting to block her grandmother's proposed conservatorship, and claimed Shelia was trying to liquidate all of John's assets and freeze out his 7 children. She also insisted her father was not in a coma and was improving every day.

We're told family insiders think Cleopatra made the move based on her fears about having access to Singleton's estate -- reportedly worth somewhere north of $35 million -- but also when she'll get it. We're told she thinks Shelia will make it impossible for her, and others in the family, to gain access to Singleton's money.

Our sources say Singleton absolutely remains in a coma -- albeit a medically induced one -- but everyone in the family remains hopeful he'll recover.

As for Cleopatra's concerns about Shelia controlling the estate? Another fact is ... John's mother is his longtime business manager, so it would seem to make perfect sense she handle his professional decisions ... and we're told that's why she filed for the conservatorship.

We're told Shelia is denying any plot to cut off John's children from his estate.

Still, Cleopatra's mistrust is clear in that she's suggesting John's son, Maasai or his father, Danny be appointed conservators instead of Shelia. We're told Danny is fully in Cleopatra's camp ... as is Singleton's current GF, with whom he reportedly has a 1-year-old son.

We reached out to Singleton's camp for comment, but no word back. Ditto for Cleopatra.

A judge's ruling is expected soon on who will call the shots as John's conservator while he remains incapacitated.