“Custody decisions are owed a high degree of deference. Appellate courts do not have the advantages of a trial judge in making findings of fact upon contradictory evidence, as most assuredly would ensue if fresh evidence were admitted in this case. Most requests for assistance from the Office of the Children’s Lawyer come from trial courts, for this reason. As pointed out in B (A.C.) v. B. (R.), 2010 ONCA 714, over a nearly 17 month period during which 5548 referrals were made to the Office of the Children’s Lawyer, all but two came from the Superior Court of Justice and the Ontario Court of Justice.”