Once something is created in a Phase it will exist in all subsequent phases, unless it is demolished in a future phase. the demolished items will not show up in any phase after they have been demolished. For example you have 3 Phases, Existing, Phase 1 New Build & Phase 2 New Build.
The existing Phase has a door (Door1) and is unaffected by the works carried out in Phase 1, but it is removed and replaced by Door1A in Phase 2. New doors (Door2 & Door3) are created in Phase 1 but Door3 is only a temporary access door that is Demolished in Phase 2 and replaced with Door4, an additional door (Door 5), is also added to Phase 2.
In the case outlined above A door Schedule with its phase set to Existing, would only show Door1. A door Schedule with its Phase Set to Phase 1 would show Door1, Door2 & Door3. A door Schedule with its phase set to Phase 2 would Show Door1A, Door2, Door4 & Door5.
I hope that makes sense and helps you visualise phases.
Darren