Got it... makes sense... this is what I was wondering...It says “for the Principal Applicant and all dependents aged 18 and over, whether accompanying or not” you will need to consider your wife’s brother too I think.. I filled it out only for my parents the first time. Now they have asked mine too.. I’m over 18 and not their dependent, and not accompanying them( as I am already in Canada) but still they are asking me to fill additional info form for myself. Better safe than getting this request twice like me I think
Then I think ... I need to fill this form for my wife and her brother both along with my wife's mother. That means I will have to fill 5406e form... 3 times in total...