To merge independent projects the best option is to use the Merge Tool, this tool is described in the User Manual, Chapter Data Management.

There are different applications when to use the Merge Tool:

a) The Merge Tool can be used to merge derived projects into the Base (Master) project.
b) The Merge Tool can be used to merge two independent projects.

In case of Option b) conflicts will be listed and you will have to assign manually which values should be taken from project A to project B.The attached file explains how to use the Merge Tool in that case.