Analytic subordination for bi-free convolution

In this paper we study some analytic properties of bi-free additive convolution, both scalar- and operator-valued. We show that using properties of Voiculescu's subordination functions associated to free additive convolution of operator-valued distributions, simpler formulas for bi-free convolutions can be derived. We use these formulas in order to prove several results about atoms of bi-free additive convolutions.