This contribution presents a study of trilinear Higgs couplings in models with two Higgs doublets with an additional real (complex) singlet, the N2HDM (2HDMS). These models differ mainly in the triple Higgs couplings (THCs). We investigate the parameter spaces of the models, while being in agreement with all theoretical and experimental constraints. The two lightest Higgs bosons are assumed to be the $h_{95}$ and the $h_{125}$, the Higgs boson observed at the LHC. We analyse methods for distinguishing between the two models via their differences in the THCs at future collider facilities, for instance, the International Linear Collider. We find that at tree-level di-Higgs strahlung can only distinguish between the models when looking at final states containing at least one $h_{95}$. These differences strongly decrease with large values for the singlet VEV $v_S$.