We note that using Ap as a measure for available distortion pathways only accounts for distortion energies when treating the 3D framework isolated from A + . Any directional interactions, such as HBIs between A + and the 3D network, give A + a more active role and thus produce larger variability in B, as found in [(CH)3NH2]M(HCOO)3 (M 2+ = Mn 2+ , Fe 2+ and Cu 2+ ) and [C(NH2)3]M(HCOO)3 (M 2+ = Mn 2+ , Co 2+ and Cd 2+ ), with B varying between 21.3 and 27.2 GPa. HBIs thus strengthen the overall framework by making any network distortions energetically more demanding, resulting in an increase of B overall.