Yes, that is an annoying things about the trusted list. I have asked to be on a trusted list for a specific person with the intention of adding the grandparents. Then I discover that I have to go back and ask to be on the trusted list for each of that persons parents, before I can start adding the grandparents to the tree. This is only for those profiles that do NOT have the OPEN (White icon at top right) status.
And if the profile manager does not respond, to your request, that makes things even more difficult, because then you have to wait for a month (30 days) before you can do anything further on that profile.
It takes a bit of time to understand how the system works. I joined in December 2016, so I have been here for less than 6 months, but I already know my way around, have added over 500 names and am enjoying myself immensely.