Multiple projects for each part of project

if they are seperate nad they are lnked make sure that in the schedule calculation that ignore relationships to and from other projects is NOT checked.

if you want to combine them into one project you might want to put a unique identifier in front of the existing activity for each project. Lets say you have 3 projects call then A, B & C. So as not to duplicate activity numbers run a global change and add the letter A- to the activity id for all activities in project A and do the same for project B run a global change and add the prefix-B- to the existing activities and do the same for project C un a global change and add the prefix-C- to the existing activities prior to combining all three projects.

To combine them export projects B and C to xer files.

Open Project A and select file import and during the import process change the import option to ADD to Existing and import project B and then import Project B using the same import option to ADD to Existing.

Now all 3 projects are together 

Zoltan,

I have a question about your way,

Assume that there are links between these A,B and C,

is that ok to export and import XER file without breaking out the logic? 

I remember there are external dates in P6 but not sure in XER file.

Thanks,

if you export within the same database you will NOT lose the relationships. The relationship will be exported with the xer file. Within the database there is an internal ID or record number that you do not see but this is how it knows how to link external relationships. 

If you would try this on another machine then you would lose the external relationships because the internal ID or record number would be different on the other machine because the database is different.