When a split view is genuinely useful

Sometimes there is no agreement to be reached, and pretending is worse than the honest version. Two clearly stated positions, calmly held, give a young person something to think with — provided both are offered as reasoning rather than as pressure, and provided you are visibly not asking them to pick a parent.

Say it explicitly: we see this differently, here is why each of us thinks what we think, we both back you either way, and the decision is yours. That is a genuinely good thing to grow up around. What is corrosive is not the disagreement itself — it is asking them to resolve it on your behalf.