Answer:
There are 7 members on the train.
Explanation:
Grandmother is mother and mother-in-law.
Similarly grandfather is father and father-in-law.
The are four children are - the daughter-in-law, the daughter-in-law,
Hilton's daughter and Hilton's son.
a. Grandmother, mother 1
b. Grandfather, father 1
c. daughter 1, mother 2 sister 1
d. sister 2, daughter 2, and net effect is 1
e. son brother 1, net is 2
f. son 2, net is 3
g. The father or Hilton 2
Hence, there are 7 people.