They should still be able to make their own if they have their own account and are not just listed on yours (I assume that is the case since you said linked). I know with linked accounts you can copy one accounts FP+ selections to the others easily (subject to availability of course). Depending on the attraction it may be difficult to get everyone in a group that large the exact same time, but you can make overlaps. For example, if your account ahs FP for Jungle Cruise from 1:05 to 2:05, you might have to make anotehr group between 1:15 and 2:15 then go between 1:15 and 2:05. That is assuming of course that all of you want to do teh same things at the same time.
Managing 17 people could be a real chore. Good luck!