A <- B <- C

A's version is @{...a.version}

<properties>
    ...
    <yourCdep.version>
    ...
</properties>

<dependencyManagement>
    <dependencies>
        ...
        <dependency>
            <groupId>yourCdep.group</groupId>
            <artifactId>yourCdep</artifactId>
            <version>${yourCdep.version}</version>
        </dependency>
        ...
    </dependencies>
</dependencyManagement>

<dependencies>
    <dependency>
      <groupId></groupId>
      <artifactId>A</artifactId>
      <version></version>
      <optional>true</optional>
    </dependency>
    ...
</dependencies>

<dependencies>
    <dependency>
      <groupId></groupId>
      <artifactId>B</artifactId>
      <version></version>
    </dependency>
    <dependency>
      <groupId></groupId>
      <artifactId>A</artifactId>
      <version></version>
    </dependency>
    ...
</dependencies>