You can't book specialty dining until you board with a dining package. The Cel agent told you correctly. Le Voyage will not be included in any package and Eden will be super limited based on current information. Once you board you'll decide the days/times for specialties from what is left available. I understand they hold back some reservations but they also accommodate suite guests and aren't serving at full capacity because of staffing issues. This is the risk vs reward of buying a discounted package to those who pre book at the higher rate.
Linking reservations won't set you up with dining/excursions together in the cruise planner but that's an easy fix, all parties book the same and then once on board let the dining staff know you're together.
Hope this helps,
Patty