If you combine two or more Microsoft Project files into a master project and have used the same local resources within the plans, you will discover if you look at the resource sheet that the resource names are duplicated. You can assign resources from a particular subproject only to tasks within that subproject.
Instead it may be worth creating a resource pool of resources as a separate project plan with no tasks. This resource pool can then be shared across projects. The Resource Graph or Resource usage views can be used in the resource pool file to see all the assignments for all the resources in the resource pool. If you are working in Resource usage view it would be useful to see which projects resources are assigned to. This can be done by clicking the Work column heading in the sheet portion, clicking the Insert key and adding the Project field.
If you combine the individual projects into a master project, as you try to expand the individual projects, you will get a message advising that the file shares resources from a resource pool and asking whether or not you want to open the resource pool.
Select the top option and click OK. You will see any resources that have been assigned in the individual plans as well as being to assign resources yourself in the master plan.
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