One example of the update of our FF design protocol, is the addition in this paper of a method for off-center virtual site parameter derivation for the modelling of anisotropic electron density. Compared to our previous method, the parameter derivation process is faster and more user-friendly. By deriving the virtual site charges and positions from the molecular symmetry and partitioned atomic electron density, we do not require any experimental data for fitting. Furthermore, since the bond, angle and Lennard-Jones parameter derivation methods are independent of the charge derivation, we can trivially add extra sites without substantially altering the force field. Notably, the mean unsigned error in the free energies of hydration of our benchmark set increases to 1.51 kcal/mol if virtual sites are not included. QUBEKit writes the virtual site positions in OpenMM .xml file format for ease-of-use.