In a multiproject environment, assembly takes wrong dependencies

With a projectstructure like 'Project/

' packaging the client as a fat jar-with-dependencies, it works fine using the following configuration.
=== etc/fatjar.xml ====
<id>fat</id>
<formats><format>jar</format></formats>
<includeBaseDirectory>false</includeBaseDirectory>
<fileSets><fileSet>
<directory>target/classes</directory>
<outputDirectory>/</outputDirectory>
</fileSet></fileSets>
<dependencySets>
<dependencySet>
<outputDirectory>/</outputDirectory>
<unpack>true</unpack>
<scope>runtime</scope>
</dependencySet>
</dependencySets>
</assembly>
=== pom.xml ===
<?xml version="1.0"?><project>
<version>0.3-SNAPSHOT</version>
<modelVersion>4.0.0</modelVersion>
<groupId>mygroup</groupId>
<artifactId>myapp-client</artifactId>
<name>My Application</name>
<dependencies>
<!-- stripped -->
</dependencies>
<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.1</version>
<configuration>
<descriptors><descriptor>etc/fatjar.xml</descriptor></descriptors>
<archive>
<manifest><mainClass>path.to.MainClass</mainClass><manifest>
</archive>
</configuration>
<executions><execution>
<phase>package</phase>
<goals><goal>assembly</goal></goals>
</execution></executions>
</plugin>
</plugins>
</build>
</project>

But when I'm on the level above (packaging all) it just assembles all underlying dependencies into my clientjar, and not the dependencies of the childproject.