Here I create two simple component one is childComponent & another is containerComponent.
in my case it is -
as shown below -
Go to your containerComponent in apps/blog/component/content folder.
Under containerComponent node create a nt:unstructured node with a name of cq:template.
Note : name must be cq:template.
Step : 3
Copy par node from /content/blogSite/jcr:content node.
Paste this node under containerComponent/cq:template node in your project and rename it as parsys. In my case it is apps/blog/component/content/containerComponent/cq:template.
your structure looks like -
Step : 4
Delete containercomponent node from cq:template node as we only want childcomponent under containerComponent. new structure looks like -
Step : 5
in containerComponent.jsp file just include this parsys node using cq:include.
my code for containerComponent.jsp is
<b>Container Component with default component in parsys</b><br/><br/>
<cq:include path ="parsys" resourceType ="foundation/components/parsys" /><br/><br/>
<b>End of Container Component</b>
Note : path property of cq:include tag must have the same value as that of the name or the parsys node under cq:template.
Note : If you don't want to see your childComponent in sidekick then just change it's componentGroup property with .hidden & it will disappear from sidekick.
now when you drop containerComponent from your sidekick you will see a screen like this -
github repository link