In contrast to Large–Eddy Simulation (LES) of single-phase flows, the LES of two-phase flows with moving boundaries is at an early development stage. The presence of the phase interface results in additional subgrid scale (SGS) terms in the LES formalism, and existing modelling approaches cannot be simply transferred from single to multiphase flows. Recently, Kobayashi (2018) proposed a regularised scale similarity type (SST) model which prevents backscatter of energy from the small scales to the large scales and counteracts destabilisation of SST models. The goal of this contribution is a combined a priori and a posteriori analysis of a modified version of Kobayashi‘s model in the context of a two-phase flow with moving boundaries.