Post # 1
According to Thai culture, Invitations for weddings are to be given to your guests formally in person. Since modern times has made that more difficult, there is usually and apology at the bottom of the invite for not being able to do this.
How would I word that apology without switching to first person?
Post # 3
Perhaps “Sincere apologies for ________.” Formal sounding, much like when businesses sometimes apologize.
Post # 4
Post # 5
What the Thai norm is is to include a preprinted card insid ethe envolope when one can not hand deliver. So the ones you do hand deliver do not say you could not do so.