WASHINGTON - Federal officials said Friday they plan to return up to 200 children a day to their migrant parents to comply with a federal court order issued in a lawsuit filed in response to the Trump administration’s immigration crackdown on the U.S.-Mexico border.

At a hearing Friday in U.S. District Court in San Diego that marked the latest step in the reunification effort, Judge Dana Sabraw praised the government’s “substantial” efforts to reunite more than half of the 103 youngest children taken from their parents by Tuesday’s deadline and acknowledged that some children could not be reunited with adults immediately.

But he also ordered the government to carry out an orderly process for the larger group after initial reports that one parent of younger children was stranded at a bus station and that others were reunited without advance notice, some late at night.

“So much of this is really just common sense and common courtesy,” Sabraw said during a 90-minute hearing Friday in the class-action lawsuit filed on behalf of migrant parents by the American Civil Liberties Union. “There shouldn’t be anything mysterious about it. It should be transparent and easy to do. It should be a very straightforward process.”

Shortly after the hearing, the government filed the broad outlines of its reunification plan with the court, saying it intended to identify six to eight locations to process the larger group of 2,551 older children on a rolling basis starting Friday. It remains unclear whether the parents and children will be detained together or released.

All told, the government separated more than 2,650 children and their parents under Trump’s “zero tolerance” policy, which the administration ended last month, or before that policy took effect.

Officials also signaled late Friday that not every family will be reunited, which also occurred with the smaller group of some 100 children age 5 or younger. Some parents did not regain custody of their children because of the parents had criminal records, were deported before reunions could be achieved, and for other reasons.

In the court filing, officials warned the judge that his order to speed the reunifications increased the safety risks for children, including the possibility that as many as 175 children would end up with adults who are not their biological parents.

Sabraw had earlier ordered the government to forgo DNA testing of all adults and to skip background and fingerprint checks of all residents in the homes where the children will live unless there was a safety concern.

Advocates had protested that such testing was creating delays and had previously occurred only when officials doubted that the adult concerned was the parent or if officials had concerns about safety.

But Chris Meekins, chief of staff for the Office of the Assistant Secretary for Preparedness and Response, the unit at the Department of Health and Human Services that is helping lead the reunification effort, said in a statement filed Friday that the “faster reunifications” may land children in “potentially abusive environments.”

Also Friday, the judge ordered the government to provide the ACLU with more information about the separated parents and children and at least 12 hours’ notice before reunifications so that advocates could book hotel rooms or find other places for the newly reunited families to stay.

Lee Gelernt, the ACLU lawyer who represents the parents, said “there were lots of glitches” in the initial reunions of parents and children under age 5.

Justice Department officials have said they reunited more than half of the younger children, and said some 45 could not be returned for safety reasons or because their parents had been deported or were in criminal custody.

On Friday, Sabraw also signaled that he was inclined to have the U.S. government shoulder the travel costs for parents trying to reunite with their children, as the ACLU requested, though the issue was unresolved.

Justice Department lawyer Sarah Fabian told the judge that it was a “huge ask” for the government to pay travel costs and that such payments were not in the government’s budget.

To reduce costs, she said, the government had moved parents to immigration detention facilities closer to their children. The judge said he would decide the issue Monday, when another hearing is scheduled in the case.

Fabian said the next wave of reunions are likely to take place in fewer locations because the children involved are older, and lawyers in Texas expect many to occur in that state, where thousands of migrant families were initially apprehended.

Trump ended the family separations before the judge’s order last month. They ignited international condemnation and concern for the physical and emotional welfare of the separated families. A Honduran man strangled himself after officials took his son, and Republicans and Democrats alike criticized the policy.

Since the reunifications began, most parents of younger children have been released with ankle monitoring devices pending hearings in immigration court.

The scenario for the older children remains unclear.

The Trump administration has called for migrant families to be detained together, possibly in military installations, until they either prevail in their asylum claims or are deported.

A recent opinion poll suggests there is public support for detaining families, even among Americans who opposed family separations. A Washington Post-Schar School poll released last week found that 7 in 10 Americans opposed separating children from parents who crossed the border illegally, but 58 percent said they prefer that families be detained until their immigration cases are resolved.

But detaining families together sets up the possibility of future separations, because a federal consent decree says the government cannot detain children in such facilities for more than 20 days. Parents would have to choose between waiving their children’s rights and remaining in detention with them or allowing their children to be released.