In Canada heading into the USA there have been some wild stories.

The deal here is you only approach with family members - sounds simple enough.

Case #1 two guys approach together - married under Canadian law to each other.
CBP refuses to accept they are family members

Case #2 man and woman approach together - married to each other - different last names
CBP demands that they PROVE they are married to each other.

Pretty stupid when you consider the reason for family members to be processed together... Saves time if they are going to the same place for the same reasons.

Bottom line? Some people have the IQ of a kumquat