Father gifts Son half share in house. They live together.
Few years later house is valued at 550k. Son buys father remaining share out at 275k. He doesnt add the 15% discount on the half share, so in effect has he overpaid for the half share?
Father buys his own place and moves out. Later son moves back in with father, has poat been triggered by the amount son overpaid, or does this count as a grob?