Sia‘s divorce from her second husband is getting nasty … because a custody battle just broke out with both of them hurling accusations at the other.

In new legal docs, obtained by TMZ, Sia’s estranged husband Daniel Bernard is asking the judge for sole custody of their one-year-old, Somersault Wonder Bernard, alleging she is a “serious and immediate danger” to their son, but Sia says he’s already restricted to monitored visits because of a child porn investigation.

In the papers, Daniel says, “Sia is an unfit and unreliable parent struggling with substance abuse and addiction, rendering her incapable of providing safe or stable care for Summi. I am the only safe and reliable parent for our son. I am a doctor, young, healthy, and have no criminal history or drug or alcohol addiction issues.”

According to Daniel, Sia deliberately concealed she was hospitalized in L.A. for 2 weeks, and tested positive for barbiturates and benzodiazepines, with no legitimate medical explanation. He also alleges she once concealed their child’s whereabouts and denied him visitation. All these things allegedly occurred in September.

In addition to sole custody, Daniel is also asking for regular monthly child support of $77,245 per month.

Although he was an oncologist when they first met, Daniel alleges he’s been unemployed and has no source of income because Sia “ceased all funding” of their joint company, Modern Medicine. He says he’s totally financially dependent on Sia who has had an “extremely successful and long music career.”

Sia has responded that there’s no emergency reason to grant full custody to Dan. She says Summi has been and remains safe in her custody since their separation, noting that they already agreed in August 2025 to give Dan very restricted professionally monitored visits, because he was under investigation by the LAPD and DCFS over “illicit child pornography” allegedly found on his computer hard drive. She says she demanded the monitoring after being informed of the investigation.

Dan vehemently denies involvement with child porn … and says he believes Sia “planted evidence” in order to restrict his time with their kid.

Sia says she understands the investigations have been inconclusive and are now closed, but says that does not alleviate her concerns of Summi spending unsupervised time with him. She is open, however, to additional custodial time for Dan so long as there is an experienced child caretaker present, like Dan’s mother or a nanny. She says she’s not open, however, to a drastic step away from their current custody arrangement.

As for her sobriety, Sia says she’s been sober for over 6 months, and says she has repeatedly agreed to drug testing for both her and Dan, claiming it was Dan who refused to get drug tested on a regular basis.

She says it’s true that she suffered from substance abuse 15 years ago, but recovery has been a “cornerstone” of her life.

She says “Dan’s attempt to weaponize my past sobriety journey… serves no legitimate purpose and is intended only to distort the facts and undermine my credibility.”

We broke the story … the “Unstoppable” singer pulled the plug on their marriage back in March, filing for divorce after only 2 years of marriage.

At the time, Sia listed “irreconcilable differences” as the reason for the split and asked for legal and physical custody of their baby. Sia said she was open to visitation for Daniel.

Daniel’s also been fighting Sia over spousal support … a couple weeks ago, he asked the judge to order her to pay him over $250,000 per month.