I'm not sure if I am understanding this correctly, do I have to go into S60RGB.h change the KC_NO (next to kc30) to kc31.
  k00, k01, k02, k03, k04, k05, k06, k07, k08, k09, k0a, k0b, k0c, k0d, k0e, \
   k10, k11, k12, k13, k14, k15, k16, k17, k18, k19, k1a, k1b, k1c, k1d, \
   k20, k21, k22, k23, k24, k25, k26, k27, k28, k29, k2a, k2b,      k2d, \
   k30, k31, k32, k33, k34, k35, k36, k37, k38, k39, k3a, k3b,           k3d, \
   k40, k41, k42,           k46,                     k4a, k4b, k4c, k4d  \
) \
{ \
   {k00, k01,   k02, k03,   k04,   k05,   k06,   k07,   k08,   k09,   k0a, k0b, k0c,   k0d, k0e}, \
   {k10, k11,   k12, k13,   k14,   k15,   k16,   k17,   k18,   k19,   k1a, k1b, k1c,   k1d, KC_NO}, \
   {k20, k21,   k22, k23,   k24,   k25,   k26,   k27,   k28,   k29,   k2a, k2b, KC_NO, k2d, KC_NO}, \
   {k30, k31, k32, k33,   k34,   k35,   k36,   k37,   k38,   k39,   k3a, k3b, KC_NO, k3d, KC_NO}, \
   {k40, k41,   k42, KC_NO, KC_NO, KC_NO, k46,   KC_NO, KC_NO, KC_NO, k4a, k4b, k4c,   k4d, KC_NO}  \
Like this, and then go into keymap and add an extra key into every fourth row for each KEYMAP ?
Edit: If so I did this and I am receiving errors when running the make command (previously to this I already flashed custom working firmware onto my other PCB).