Lines are being drawn and a family fight is brewing over a potential conservatorship for former MTV host Matt Pinfield.

According to new legal docs, obtained by TMZ, Matt’s girlfriend, Kara Brown, and his brother, Glenn, claims Matt’s daughter Jessica is isolating Matt from the rest of the family and trying to cut them out from his life.

Matt, as we first reported, is hospitalized after suffering a medical emergency. Jessica claims he’s incompetent and unable to make decisions on health and finances. She filed for a conservatorship and voiced fears his GF would drain his bank account if left unchecked.

Kara says she took Matt to the hospital after a nasty fall and stayed by his side … until Jessica showed up one day and accused her of being on drugs and blamed her for Matt’s stroke.

Matt’s GF claims Jessica was trying to destroy her credibility with hospital staff and she says the next time she went to visit Matt she learned her visitation rights had been stripped. She claims she was escorted out of the hospital. Kara says she’s since been completely cut off from what’s going on with Matt.

Meanwhile, Matt’s brother claims Jessica blindsided the rest of the family — including Matt’s mother and sister — when she filed for the conservatorship. He says Jessica’s is gatekeeping medical information on Matt and is excluding the rest of his loved ones.

Glenn goes to bat for Kara too and says he’s troubled by Jessica’s actions.

Jessica’s already been appointed temporary conservator, but Kara and Glenn are opposed to this and want the court to reconsider before things move forward.