To have the composition of two monads be a monad itself, we need a distributive law natural transformation satisfying certain coherence laws.
I'm interested in the strict 2-monad case, i.e. a strict 2-functor equipped with unit and counit natural transformations that satisfy the zig-zag equations on the nose.
I presume in such a case it's still possible for the distributive law to satisfy its coherence laws only up to a modification. If so, what coherence laws do those modifications have to satisfy?