build-with-import.md

libary.xml

<project name="buildlibrary" default="hello">
  <target name="hello" hidden="yes">
    <echo message="Hello World!"/>
  </target>
</project>

build.xml

<project name="A Project" default="hello">

  <import file="library.xml"/>

  <target name="hello" depends="buildlibrary.hello"/>

</project>

Targets from the imported file are prefixed with the name from that file.

Documentation: https://www.phing.info/phing/guide/en/output/chunkhtml/ImportTask.html