I'm not sure what type of professional, but I would want to SPEFICY that the recommender have experience and training with giftedness, ADHD, twice exceptional students, and any other specific conditions that are subsequently diagnosed by a professional with experience with twice exceptional student (we see a pediatric neuropsychologist).
It might also be worth specifying how you would go about paying for this professional evaluation (split 50/50?), how recommendations will play into your children getting medical treatment, medication choices, frequency and type of therapy, and educational decisions.
FWIW I have two 2E kids and separated from my ex when they were 3 and 7, so I have BTDT with arguments over medication, therapy, and conditions diagnosed post-divorce. Technically my daughter's therapist didentified in the parenting agreement even has the power to make my ex come to therapy.
Also if you haven't thought about it, consider including some sort of plan for educational enrollment decisions and college savings. My lawyers said most people don't, but we did, because that's definitely a thing parents of teenagers are arguing about when they get there.
