That is correct, Viewliners only have roomettes, bedrooms, and accessible rooms. So, the above conversation pertains to bedrooms.

Bedrooms (including on Viewliner) have an official maximum capacity in the sleeping configuration for parties including children as follows: Two adults and two children, or one adult and three children, or four children. But officially, two adults and three children is not allowed. However, you could get two roomettes and split the party accordingly.