If your children are under the age of 22 they are dependants under Canadian Immigration Legislation.
5.13. Who qualifies as a dependent child?
R2 and Section 6 in this chapter describe who qualifies as a dependent child. In order to meet R2(b)(i) of the definition of “dependent child”, a child must be under 22 years of age and not a spouse or common-law partner on the date when the IMM 1344AE is received by CPC-M, and not a spouse or common-law partner when the visa is issued, and when they arrive in Canada.
I suggest you real OP2
http://www.cic.gc.ca/english//resources/manuals/op/op02-eng.pdf section 5:10 and 5:11 for information on non-accompanying family members.
5.10. Non-accompanying family members
Applicants must declare all family members when applying for a visa and must again declare all family members, whether accompanying or not, prior to obtaining permanent resident status. Permanent residents who did not declare all their family members on their application are reportable under A44(1) [see also “Sponsor who may be subject to an A44(1) report” (section 10.5 below) and “Misrepresentation” (section 5.22 below)]. In addition, all family members, whether accompanying or not, must be examined, unless the appropriate officer determines that they are not required by the Act or the former Act to examine the family member [R117(10)]. Family members who were not declared and examined are excluded from the family class and may not be sponsored at a later date as per R117(9)(d) unless R117(10) applies.
Non-accompanying family members must undergo medical examinations. They must also establish that they are not inadmissible for criminal or security reasons. If the requirement for minimum necessary income is applicable, sponsors must demonstrate that they can support all family members, including non-accompanying family members