So, noting that the mental health conditions are Bipolar Personality Disorder and Dissociative Identity Disorder, the legal responsibility of the lawyer representing her is to essentially to represent your former spouse to the best of the lawyer's capacity. If they were to go to the Court and say, "My client is suffering two mental disorders and is a danger to the kids", he wouldn't be upholding his obligation to his client as her lawyer, would he?
You should expect they will "downplay" her mental illness if it benefits her case to do so. It's your job, as the opposing party, to try and discredit their claims in court and show the judge that these issues pose a risk to the children, if that's what the basis of your case is.
Now, plainly speaking, nearly every parenting dispute that requires court intervention is plagued by at least one party who has some scope of a mental health issue. If that wasn't the case, it's fair to say you probably wouldn't be in court to decide parenting matters. The most common, I would suggest, are Bipolar and Narcissism, so finding a lawyer who 'specialises' in these issues is essentially the same as finding a family law lawyer.
As for the case management conference, this is usually a conference to try and help you and other party reach an agreement of your own accord, rather than having the Court decide for you. You might find this useful:
http://www.familycourt.wa.gov.au/_files/Case Assesment Conferences 011210.pdf