It depends on the predecessors. The short answer is I separate those tasks from the others by removing predecessors that point to the tasks that will still be worked on, then I put a dummy task in that is set to a really long duration (whenever you think it will be resumed) and have all the "on hold" tasks rely on the dummy task.
Something like
Dummy Task Duration 90 Days (or whatever)
Task 1 Predecessor set to Dummy task
Task 2 Predecessor set to Task 1
Task 3 Predecessor set to Task 2
When I want to resume, I set the dummy task to Complete and that triggers the Task 1 to start.