How many persons attend the seminar between M and his

Solution

Two persons were seated between P and M’s father and neither of them attends the seminar in November. The one who was seated second to the left of P attend the seminar in May. M and his father were immediate neighbours. Two persons were seated between M and the one who attend the seminar in September. The one who attends the seminar in September is nephew to P and both were seated adjacent to each other. O, who is the son of M was seated to the immediate right of his sister and attend the seminar after M but not immediately. Q is married to the only sister of the one who attends the seminar in June and was seated to the immediate left of M’s daughter. Two persons were seated between N and M’s wife. Q is from 1st generation. P is not the brother of M’s wife. Two persons were seated between Q and the one, who attended the seminar June. The one, who attended the seminar in May doesn’t face the one, who attended the seminar June. O and P are not neighbours. Two possibilities in blood relation.  Hence, case 1b and case 2a are invalid because O was seated to the immediate right of M’s daughter and Q was seated to the immediate left of M’s daughter. Case 2b is invalid because P cannot attend the seminar in June (possibility 2 of blood relation diagram) So, possibility 2 of blood relation diagram is invalid. Only one female attend the seminar after June. S and her brother attend the seminar on consecutive months. Two persons attend the seminar between P and R. T attend the seminar in August. So, the final solution is