Liesel Pritzker, the millionaire heiress whose 2002 lawsuit blew the lid off the secret financial dealings and inner struggles of the Pritzker clan of Chicago, obtained a key court ruling on Friday that could soon force her father Robert Pritzker to respond to questions about his role in actions that drained $2 billion in assets from trusts benefiting her and her brother, Matthew Pritzker.

Technically, the ruling dismissed the siblings’ case. But Cook County Chancery Court judge Patrick E. McGann carefully laid out a legal blueprint that allows them to re-file a complaint that will almost certainly allow them to move beyond the dismissal phase of the suit and begin questioning their family–McGann even lifted an earlier stay he had put upon Liesel and Matthew’s request for discovery.

The siblings have 28 days to amend their complaints. The ruling didn’t consider whether Liesel and her brother Matthew have enough facts to support their allegations against Robert, their uncle Thomas and former attorney Marshall Eisenberg. But in regards to the legal theory of the case, McGann wrote, “the allegations make out a claim for breach of the trustee defendants’ duty of loyalty and plaintiffs’ claims are sustained on that basis.”

“It didn’t say any part of our theory wasn’t legally viable,” said Lazar Raynal, lead attorney for Liesel Pritzker. “The suit’s going forward, but [McGann] is saying: ‘Here’s how I want you to plead this’.”

In a statement, Robert Pritzker’s attorney Lowell Sachnoff acknowledged the ruling will allow the case to move ahead. He added: “We are confident they will show that Robert has done nothing wrong.”

Once Liesel and Matthew re-file their complaints in accordance with McGann’s ruling, the rest of the family will have four weeks to respond. An attorney working for several Pritzker defendants said that while it’s possible, even likely, that the family will make another motion to dismiss, the judge’s ruling on Friday makes it clear that the suit will almost certainly move past that motion.

The attorney said flatly that the “judge just didn’t buy the arguments” made by Thomas and Robert Pritzker and Marshall Eisenberg. “It’s a pretty significant ruling,” he conceded.

The most crucial part of the ruling may be McGann’s decision to allow discovery. The Pritzkers value their privacy, so the ruling increases pressure on them to find a way to settle the case. Raynal and Daniel Webb, the former federal prosecutor who represents Matthew Pritzker, said in a joint statement that they “look forward to questioning the defendants and others to hear their story and their explanations for why our clients’ trusts were emptied while everyone else’s trust accounts continued to grow beyond all bounds.”