This summary is not the rule. The rule text controls.
Before a disposition hearing happens, everyone involved in the case has to share information with each other ahead of time. At least five court business days before the hearing, each party must give the other parties, anyone who has the right to be at the hearing, and the judge a list of the witnesses they might call. They also need to include a short summary of what each witness is expected to say, along with a list of the legal and factual issues they plan to raise.
This rule exists so nobody gets caught off guard at the hearing. Everyone should know ahead of time what evidence and arguments the other side plans to bring up. That way, the judge and all parties can prepare properly and the hearing runs smoothly.
The rule also says this isn't a one-time deal. If new witnesses come up or plans change after the initial list is shared, parties have to keep updating that information right up until the disposition hearing starts. This keeps everyone on the same page as the case moves forward.