On Bemidbar 3:38, Baal Haturim points out that there is a pasek (a vertical bar) between Moshe and Aharon and his sons. He explains this as there being Moshe in one place, alone, and Aharon and his sons in another place, alone.
The motivating factor would appear to be the pasuk which calls out "darshen me," for it works on top of trup, often coming between a meshares and its melech.
But doesn't this derasha go against the pasuk? The pasuk intended that those encamped -- chonim, plural, east before the Tent of Meeting were all these people. Then, this divides them. Where and how, precisely? There might be an answer.
My real issue with this interpretation is that that vertical bar is no pasek! The meshares before it is a munach, and it is in the clause of a revii. This is no pasek! Rather, it is the marker of a munach legarmeih, showing that that munach is not a meshares but rather a melech! Unfortunately, various signs are reused by the masoretes, and this can lead to confusion. But this is no pasek.
Would Baal Haturim darshen it if he thought it was not really a pasek? I doubt it. It is no longer "weird," meaning unexpected and out of place. Rather, this is the trup we would expect, exactly where we would expect it. He does not darshen every pashta, or every etnachta. So even though the munach legarmeih marks a stronger division, the entire derasha still falls apart.
Why should there be a munach legarmeih there? The standard rules of continuous dichotomy. Where there are three of more words in a clause, it must be subdivided with a melech appropriate for that context. Since Moshe veAharon uVanav consists of three words, it must be subdivided. And since the sons belonged to Aharon, presumably, and not to Moshe, the proper place to divide it was after the word Moshe.