Visitor visa, help with form 5645e

[ravs9]

Hi, my parents are applying for visitor via for Canada. While filing the form imm 5645e, he has filled his and mum's details and thier children's details. in section C it asks for brothers and sister details.

My question is does he only need to fill his borthers and sisters detail, or my mum needs to fill as well but in a seprate form to enter her siblings details ?

Thanks