Re-importing MS Project files
Merging MS Project Imports into an Existing PM3 Project
When importing into a non-empty PM3 project, the system uses UniqueIDs to match and merge items correctly.
Understanding IDs vs UniqueIDs in MS Project
Each task (or row) in MS Project has two key identifiers:
| Field | Meaning |
|---|---|
| ID | The task’s position/order in the project (can change if tasks move) |
| UniqueID | A permanent, unique identifier for the task (remains fixed over time) |
Key Behavior of UniqueIDs:
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If you reorder tasks, the ID changes, but UniqueID stays the same.
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If you delete a task (e.g., UniqueID 10), that number is not reused.
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A new task will receive the next available UniqueID (e.g., 11).
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You can choose to display the UniqueID column in MS Project to track this.
How PM3 Uses UniqueIDs
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PM3 records the MS Project UniqueIDs of the items it imports.
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This enables accurate re-import and synchronization.
How the Merge Works:
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If an imported item (e.g., a workstream) has UniqueID 11…
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And PM3 already has an item with MS UniqueID = 11,
➤ PM3 updates the existing item with new data. -
If no match is found,
➤ PM3 creates a new item and stores the new UniqueID.
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This ensures:
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Changes in names, dates, and even new tasks are handled properly on re-import.
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There’s no duplication, as long as UniqueIDs are maintained.
⚠️ Important Caveat: One MS Project File per PM3 Plan
Only import files from one MS Project source into a given PM3 plan.
Why?
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UniqueIDs are unique only within one MS Project file.
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Two different MS Project files may have conflicting UniqueIDs (e.g., both have a task with UniqueID 11).
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This causes confusion and mismatches in PM3.
To ensure correct merges and updates, stick to a single MS Project file per PM3 project.