Combine XPO Tool

Combine XPO Tool is a command line program that combines a set of interdependent XPO files into a single XPO.

 For example, if a team of developers is making code changes to different aspects of an application, they can use this tool to merge those changed files into one XPO file.

As of AX 2012 R2, the Combine XPO Tool is available in the Microsoft Dynamics AX\60\Management Utilities folder. 

for more information :

https://msdn.microsoft.com/EN-US/library/jj225589.aspx