In P6, I define a User Defined Field and create a Global Change to set that field equal to BL3 Finish minus Finish. When I apply it, it only runs on activities. Is there a way to make it roll up to the WBS Summary levels above, like in MS Project?

Overview:
This is a well-known limitation of Primavera P6. Unlike MS Project, P6 does not natively support automatic Roll Up of User Defined Field (UDF) values to WBS Summary levels.

Why This Happens:
The Global Change function in P6 only processes activity records. WBS Summary rows are not true activities — they are calculated display rows, and P6 does not aggregate UDF values from child activities up to parent WBS nodes automatically.

Workarounds and Solutions:

• Option 1 — Global Change on WBS Summary Activities:

If you are using Activity Type = WBS Summary, you can target those in a Global Change. However, P6 still cannot calculate a rolled-up value from child activities within the Global Change logic itself, so this does not truly solve the problem.
• Option 2 — P6 Integration API or SDK:

If you are on P6 EPPM, you can write a custom script using the P6 Integration API to loop through WBS nodes, aggregate child activity UDF values, and write the result back to a WBS-level UDF. This is the most robust solution but requires development effort.
• Option 3 — Export to Excel via XER or Excel Export:

Export your schedule data, perform the Roll Up calculations in Excel using SUMIF or Pivot Tables, then re-import. This is a common practical approach used on many projects.
• Option 4 — External Reporting Tools:

Use reporting tools such as BI Publisher, Primavera Analytics, Power BI, or Excel-based dashboards to perform the aggregation outside of P6. This avoids the limitation entirely and is the recommended approach for senior schedulers.
• Option 5 — Redesign the UDF Approach:

Consider whether the Roll Up is truly needed inside P6, or whether the summary-level variance (BL3 Finish
• Finish) can be reported at activity level only and summarised externally.

Key Takeaway:
P6 does not support automatic UDF Roll Up to WBS Summary levels — this is a genuine product limitation. The most practical solutions are either Excel-based post-processing or external reporting tools. If you need this natively inside P6, a custom API solution is the only true path forward.

Tip:
When designing UDF strategies in P6, always consider whether the data needs to appear at WBS level — if so, plan for an external calculation step from the start.