A domain can be customized through the host.xml descriptor file in the directory /domain/configuration of WildFly. Here, we can see the default configuration:

<servers>
 <server name="server-one" group="main-server-group">
 <!--
 ~ Remote JPDA debugging for a specific server
 ~ <jvm name="default">
 ~ <jvm-options>
 ~ <option value="-agentlib:jdwp=transport=dt_socket,address=8787,server=y,suspend=n"/>
 ~ </jvm-options>
 ~ </jvm>
 ~
 -->
 </server>
 <server name="server-two" group="main-server-group" auto-start="true">
 <!--
 ~ server-two avoids port conflicts by incrementing the ports in
 ~ the default socket-group declared in the server-group
 -->
 <socket-bindings port-offset="150"/>
 </server>
 <server name="server-three" group="other-server-group" auto-start="false">
 <!--
 ~ server-three avoids port conflicts by incrementing the ports in
 ~ the default socket-group declared in the server-group
 -->
 <socket-bindings port-offset="250"/>
 </server>
</servers>

We can combine the association through servers and groups as we wish.