For my family, eg we have 3 that falls on June (start, mid and end of June) so we will hold the gathering on the mid of June but at the same time not on anyone’s actual day. This is to save cost and time as everyone have work/schools so 3 parties is not very feasible. Afterall, as long as everyone gets their present, it’s a win- win for everybody 🤣. I would personally hold it on mid Dec. If you feel bad for the belated kid, can hold a small direct family gathering (mom, dad, siblings only) then leave the bigger gatherings on mid Dec 😊.
You can simply combine to save $ but make it simple for both kids. However it has to be a suitable theme or no theme but perhaps some goodies, games or their own personal fav cake design. Whatever suits your budget and make the kids happy.
itsallabout_mytwokids