Those families weren't covered by Sabraw's June ruling in the case, which spurred a massive effort to recover thousands of immigrant families the US government had separated. That's why this other group of children had been released from the government custody already.
So we don't know who those families are or what happened to them.
Pressed government attorneys on Thursday
"Isn't it important to have an accounting, simply an accounting of what happened to, how many are involved and where are they?" he asked.
Justice Department attorney Scott Stewart deployed a range of arguments to the judge that expanding the case to include families separated before June 26, 2018 is not a good idea.
He repeatedly emphasized what a significant undertaking it would be for the government to compile a new list of separated families.
Requiring that, he said, would " blow the case into some other galaxy of a task. " He called the notion of "seismic shift" and a "dramatic change."
The ACLU says it's willing to do whatever it takes to track down separated families.
ACLU attorney Lee Gelernt said the organization is ready to set up a steering committee to track down separated families.
"We're talking about little children potentially being permanently orphaned," he said.
Even if the judge orders the government to identify these families, they might not be reunited.
 After Sabraw's order over the summer, officials identified separated families and started a painstaking process to reunify them.
But there's now guarantee we would see the process play out the same way this time around.
Sabraw noted on Thursday that reunifying families is only one potential remedy.
"The alleged wrong is the government conduct of separating families as a matter of policy. , "he said.
The appropriate remedy for these other families, Sabraw said, could be determined later.
" If this motion is granted, step one, which is a very significant step, would be the accounting, " he said. "What are the numbers? Who are they?"
Pinpointing what happened is important, the judge said.
"An allegation of wrong on this scale," he said, "one of the most fundamental bond of law is to determine the scope of the wrong. "