Is it permitted la chatchilla to say havdala in shul to yotzi the minyan and have in mind not to be yotzi yourself so you can say it for your family when you get home?
Answer:
Yes, this is fine, and it was the common custom for everybody to make havdalah again at home, including the chazan, since the intention was not to fulfill the personal mitzvah of havdalah in shul.
See for instance Shulchan Aruch HaRav 296:17.
Best wishes.
