Hi,
as stated in the post Arun mentions Web Part Containers aren't really meant to be used that way.
What would you hope to achieve? Should the widget be manageable by editors? Want it to be reusable component?
You could add a Widget Zone after your Web Part and make sure the "container" styling/html is surrounding both! Or just add a second Web Part... You could even include the logic inside the code of the first Web Part.