Guardian ad Litem - GAL - the children's representative.
Early in my divorce my lawyer said a GAL wasn't needed. About 5 years later we got a GAL and have used those services twice, once for the custody case, again for modification of parenting time. Ours happened to be a lawyer, others have had social workers or others. Lawyers sometimes are frustrating, they're too willing to make settlements with half measures.
My L recommends requesting a GAL before the judge acts on his/her own. That way you can also say "we request John Smith be appointed a GAL" and if the judge approves, you have a bit more say/control over the choice of GAL. Sometimes, the GAL has little experience, has biases, etc. If you suggest someone that you know to be a good choice, and is respected and experienced in your jurisdiction, you're more likely to get a good GAL who will cut through the BS and work for the kids.
After the GAL is appointed, then the parents pay for GAL services. Sometimes not in equal shares, depending on who has money available. The judges will order one parent to pay for it all if the other can't pay and not think twice.
Both times the court excused ex from paying her portion of the GAL fees. That despite ex never submitting any income data to the court.