You've got the right idea. However, the number of ways dividing $6$ people into two groups of three is not 20. It is 10. You may want to read more about it here.
The other case you're missing is when the six people form a cycle of their own - i.e. if you place the family members on a round table, each person forms a pair with their neighbour. The number of ways in which this is done is $\frac{5!}{2} = 60.$
Thus, the answer is $$10 + 60 = 70$$