Hi Julie,
There are currently 23 travellers booked to visit Vietnam this Christmas with a further 2 travellers provisionally booked. Of the 23, 5 of the group have booked to take the add-on.
The Tour Manager has not yet been allocated for this trip - usually, the tour manager will stay on for the Cambodia add on but if you ask again a little closer to departure I'll be able to advise who this is and check whether or not they will be joining you or if a Local Guide will accompany you.
Kindest regards,
Julia