I noticed in your topic's subject line you wrote "our son". Good for you. However, I doubt his mother could or would use that phrase. Yes, it's okay to say "my child" but can both parents also readily say "our child" as you did? That ought to be a real indicator to any professional.
My Custody Evaluator was a child psychologist who also taught at the local university. His evaluation took 5 months, a month longer than allotted since my bi-lingual Ex, a certified medical/legal translator at the time, chose to answer the psych tests in her parent's native language and so the CE had to hire someone to translate them. His thorough report was about 10 or 11 pages (some members here relate their reports were as much as 100 pages!) and the summary stated,
"Mother cannot share 'her' child but Father can." That spoke volumes and so it should for you. If a parent is so controlling, demanding, dictatorial or entitled that cooperation or sharing is an issue, then that ought to be a huge red flag
to the evaluators, other professionals and the court. Understand that unless it gets noted somewhere "on the record" at court then it may be easy for the court to ignore it.
