Harmony Montgomery seen with father, stepmom after they claimed they last saw her, police say

New Hampshire authorities now say missing 7-year-old Harmony Montgomery may have been last seen with her dad and stepmother up to two weeks after they claimed she moved back in with her biological mother, who lost custody in 2018.

Authorities previously said they believed Harmony had last been seen on the day after Thanksgiving in 2019. Now they say Harmony likely disappeared between Thanksgiving Day, which was Nov. 28, and Dec. 10 of that year.

Investigators say Harmony’s dad and stepmom, Adam and Kayla Montgomery, were living out of a car following their Nov. 27 eviction from the house at 77 Gilford Street in Manchester.

"Multiple individuals have reported seeing Harmony with Adam and Kayla in the following days; however, by approximately Dec. 6–10, 2019, Adam and Kayla apparently had only their two common children, and Harmony was no longer with them," police said Monday.

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The couple subsequently had another child, who is now 1.

Police say the family lived out of two cars – a silver 2010 Chrysler Sebring and a dark blue 2006 Audi S4. Both were in rough condition. They may have spent time in Manchester’s North End.

Manchester police declared Harmony a missing person in December after they said they discovered that the girl had been unaccounted for since late 2019. She is blind in one eye, and they also allege that her father punched her in the face in July of that year – in charges they announced earlier this month.

The new development emerged as her stepmother was arraigned on amended charges Monday. Kayla Montgomery is accused of collecting welfare on behalf of the girl for more than a year after she last saw her.

RELATED: Harmony Montgomery: Timeline, everything known about girl’s disappearance

Montgomery’s attorney, Paul Garrity, asked the judge to release her on her own recognizance into a drug rehab program – but prosecutors argued that new evidence could be forthcoming in the missing girl case.

"Maybe now it looks like an innocuous theft charge, welfare fraud charges," Assistant Hillsborough County District Attorney Jesse O’Neill told the judge. "But she knows what we are going to learn as the investigation continues."

Harmony’s dad, Adam Montgomery, is also in custody – on charges of child abuse and assault, among others.

A Massachusetts judge granted Adam Montgomery sole custody of Harmony on Feb. 22, 2019, despite a criminal history of violence and drugs. The state’s Office of the Child Advocate is investigating how that happened.

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The search for Harmony continues.

Harmony is about 4 feet tall and 50 pounds. She has blonde hair and blue eyes and wears eyeglasses. She’s also blind in her right eye.

Manchester police urge anyone with information to call the dedicated tip line at 603-203-6060.

"Any information, no matter how small or insignificant it may seem, may contribute to the overall investigation," police said Monday – especially from anyone who encountered the family or saw those cars between Nov. 28 and Dec. 19, 2019.

Read updates at FOXNews.com.