Maven package phase: how to depend on package artifacts from other projects - maven

Question

I have this Maven project structure:
-- top
-- a
produces a.jar and a-capsule-fat.jar
-- b
produces b.jar and b-capsule-fat.jar
-- pkg
produces all.tar.gz, which contains a-capsule.jar and b-capsule.jar
I am using the capsule-maven-plugin to build fat jars in a couple of projects, as shown above. Normally capsule is run during the package phase. I then want to assemble the capsule jars into a tar.gz for deployment purposes. I am using the maven-assembly-plugin in project pkg to make the tar.
But the maven-assembly-plugin also normally runs during the package phase, and it's running before the capsule jars are created.
Can I specify a assembly dependency or ordering that will force maven to create the capsule jars first? Alternatively I could build the assembly in a later phase, but there are no really suitable later ones (in install? there is no post-package).
POST-ANSWER: I am including some pieces of the working code for posterity:
dependencies in pkg/pom.xml:
<dependency>
<groupId>thegroup</groupId>
<artifactId>a</artifactId>
<version>theVersion</version>
<type>jar</type>
<classifier>capsule-fat</classifier>
</dependency>
<dependency>
<groupId>thegroup</groupId>
<artifactId>b</artifactId>
<version>theVersion</version>
<type>jar</type>
<classifier>capsule-fat</classifier>
</dependency>
assembly plugin settings in pkg/pom.xml:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<id>build-tar</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
<configuration>
<descriptors>
<descriptor>src/main/assembly/pkg.xml</descriptor>
</descriptors>
</configuration>
</plugin>
pkg.xml (referenced above):
<assembly xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.2"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.2 http://maven.apache.org/xsd/assembly-1.1.2.xsd">
<id>ustc-archive-pkg</id>
<formats>
<format>tar.gz</format>
</formats>
<dependencySets>
<dependencySet>
<includes>
<include>*:jar:capsule-fat</include>
</includes>
</dependencySet>
</dependencySets>
</assembly>

Answer 1

Make sure the definition for the capsule-maven-plugin appears before the maven-assembly-plugin. When there are executions bound to the same phase, Maven uses the order of the plugin definitions in the POM to break the tie.
---- edit ----
Make sure the dependencies on a and b include a classifier:
<dependency>
<groupId>theGroup</groupId>
<artifactId>a</artifactId>
<version>theVersion</version>
<classifier>capsule-fat</classifier>
</dependency>
See if that does it.