How can I define a sort/order by for related records?

[sokulski]

So far, I've tried using the "$sort" parameter on a query, targeting the dot separated name of the nested table, like 'child.id.'

With an $eager relation that doesn't work as the the child table is queried separately and 'child.id' isn't present yet.

I tried $joinEager too, but that aliased the order by clause and the resulting error said that the field didn't exist.

Am I better off writing a modifier that sorts how I'd like and calling that via the $modify param? Or am I missing an easy way to do this?