Is there a way that you can run the 'Calculate Completion Estimates' process for all cost plans on a project at once.

Seems there are two options - run the 'Calculate Completion Estimates' from Project form Related Links and this updates the Project Financials fields Estimate at completion (pm_project.forecast_cost) and Estimate to completion (pm_project.estimate_to_completion).

The Cost Plan column for Estimate at Completion (cost_plan.forecast_cost_default_currency) and the Estimate to Completion (cost_plan.etc_cost_default_currency) doesn't update unless you click on the individual Cost Plan record and click Related Link 'Calculate Completion Estimates'.

Although the Project EAC and ETC values are correct it is nice to see the breakdown in the cost plans but if you have 20+ cost plans this will become tedious to run each month one by one.

What is the best option to get all Cost plans updated each month?

In OOB, the cost plans which are directly linked with the project are updated, but the cost plans which are linked to the project tasks of the project are not updated when selected 'Calculate Completion Estimates' on the project.

Currently, in OOB there is no functionality to update all the cost plans related to the project, as the script queries the cost plans related to the project.

The UI Action 'Calculate Completion Estimates' on Project, calls a function in the script includes "ProjectCalculateAJAX which calls "_updateEACCostPlans" function.

In this function, the glide query on "cost_plan" check if the "task" is the sys_id of the project, so only the cost plan which is directly linked to the project is updated.

As a workaround, updating the OOB script include by adding an OR query to check if the "top_task" as a project sys_id, will query all the project task records. This will check and update the records of the cost plan for the project task also.