Addendum: Towards next-to-next-to-leading-log accuracy for the width difference in the ${\mathbf{B}}_{\mathbf{s}}-{\bar{\mathbf{B}}}_{\mathbf{s}}$ system: fermionic contributions to order $({\mathbf{m}}_{\mathbf{c}}\mathbf{/}{\mathbf{m}}_{\mathbf{b}}{)}^{\mathbf{0}}$ and $({\mathbf{m}}_{\mathbf{c}}\mathbf{/}{\mathbf{m}}_{\mathbf{b}}{)}^{\mathbf{1}}$

We calculate the three-loop master integrals of Ref. [1] [arXiv:1709.02160] in analytic form. This allows us to present the fermionic contributions to the $\mathrm{\Delta }B=2$ Wilson coefficients of the $B$-$\bar{B}$ decay matrix in next-to-next-to-leading order of QCD with full analytic dependence on the mass of the charm quark in the fermionic loops.