Jean, only a profile manager can change the privacy of a profile - not even a member of the trusted list can do that. The only exception is the automatic unlisted privacy assignment that happens if you enter a date that makes a person possibly living.
You need to write to the profile manager and ask her to either open the profile or add you to the trusted list if you want to be able to work on it. If all you want to do is to connect her to her children, then you can ask the manager to do that, provided the children have open privacy. If a child is still living then that could only be done by the manager of the child's profile, but it doesn't matter very much because any living person will be unlisted and would only show as "private son" or "private daughter" anyway.
