Your medical request Would come with that for your non-accompanying dependant, and it doesn't come with an option to waive.
The request has a 30 days deadline, and you need to prove to the visa officer, reasons with proof, why you can't get in contact with the dependent.
A notarized letter or affidavit is needed also, it is at the visa officer's discretion, and you would now be granted the forms to waive.
Also, note that you would not be able to sponsor the dependent forever.
Yes, a waiver request will slow things down, with AVO, they need to peruse the documents sent, and see true reason, why you can't make contact with the dependent.
Below is a letter sent to someone on this case, for your perusal.
All family members, whether accompanying or not, are required to be examined to ensure that they are
not inadmissible to Canada. You must make every effort to have your non-accompanying family
members examined. You cannot simply choose not to have them examined. If you are unable
to meet this requirement, you must satisfy an officer that extenuating circumstances prevent you
from doing so and that you have made all reasonable efforts to meet this requirement.
If all of your family members are not examined and you are unwilling or unable to provide
supporting documentation to satisfy an officer that you have made all reasonable efforts to meet
this requirement, your application will be decided based on information available on file which
may result in the refusal of your application.
If you are unable to have all of your family members examined, you must provide the following as proof
of your efforts to have them examined;
i) A statement and supporting documentation for your attempts to have your non-accompanying
family members examined and,
ii) An explanation as to why your attempts to have your non-accompanying family members
examined have not been successful, including court documents, custody and/or separation
documents as applicable. Note: Not having custody of a child should not normally be an
impediment to having the child examined.
You must show that you have made all reasonable efforts to have your family members examined. We
will review the documentation provided and advise you whether there are sufficient reasons to consider
granting relief from having your non-accompanying family members examined. It is only in truly
exceptional circumstances, when there are clear humanitarian and compassionate grounds, where relief
may be granted from not meeting the requirements of the Act.
We remind you that failing to declare a spouse or child in your application, prior to becoming a
permanent resident, may lead to an inadmissibility finding for you, even if you have already become a
permanent resident."
