  In this paper, we give a combinatorial proof of a positivity result of Chern
related to Andrews's $\mathcal{EO}^*$-type partitions. This combinatorial proof
comes after reframing Chern's result in terms of copartitions. Using this new
perspective, we also reprove an overpartition result of Chern by showing that
it comes essentially "for free" from our combinatorial proof and some basic
properties of copartitions. Finally, the application of copartitions leads us
to more general positivity conjectures for families of both infinite and finite
products, with a proof in one special case.
