http://www.cic.gc.ca/english/resources/manuals/op/op06-eng.pdf - Page 16 - Section 6.4 said:
All family members, accompanying or not, are required to be examined during processing of an application unless a properly delegated officer has determined that they were not required by the Act or the former Act, as applicable, to be examined. Normally, any inadmissible family member would render the principal applicant inadmissible as well [A42; R23].
There are, however, two exceptions to this rule. The first is the separated spouse of the applicant. The second is the child
of an applicant in the legal custody of someone other than applicant or an accompanying family member or where someone other than the applicant or an accompanying family member is empowered to act on behalf of that child, by virtue of a court order or written agreement or by operation of law.
If an applicant’s separated spouse or the applicant’s children who are in the custody of someone else are inadmissible, their inadmissibility would not render the applicant inadmissible. However, as separated spouses can reconcile and custody arrangements for children can change, examination is required in order to safeguard the future right to sponsor them in the family class. If these family members are not examined, they are excluded from the Family Class in the future
under R117(9)(d).