The custody battle between Southern Charm stars Kathryn Dennis and Thomas Ravenel is getting even nastier.

Each is seeking sole custody of their two children aged one and three and according to RadarOnline Thursday, Dennis is now accusing her ex of dating the teen daughter of their kids' nanny.

In court documents obtained by the website, the 24-year-old alleges Ravenel, 54, 'has had a romantic relationship' with the girl and 'has encouraged the underage drinking of the nanny’s daughter [redacted] in front of the children!'

DailyMail.com has reached out to Ravenel seeking comment.

Legal fight: Kathryn Dennis, 24, is accusing her ex Thomas Ravenel, 54, of dating the teen daughter of their children's nanny as their bitter custody battle over their two kids get nastier

The couple's children, daughter Kenzie, three, and Saint, one, currently live with their father in South Carolina after Dennis failed a court-ordered drug test last June.

She subsequently entered a rehab treatment program in Southern California.

She has accused the politician of 'alienating' her from her children.

For his part, Ravenel claims the children are not safe in their mother's care.

Troubled: Dennis, who dated Ravenel from 2013 to 2015, is fighting the politician for sole custody of their kids after she completed rehab treatment for drug abuse

Concerned: The children - daughter Kenzie, three, and son Saint, one, - currently live with their father who has said he fears for their safety if allowed to be with their mother

Dennis's personal troubles have played out on screen during season four of the Bravo reality show set in Charleston.

She and Ravenel had a relationship from 2013 to 2015 and never married.