Continuous Integration Scenario

Let us say that Dev1 & Dev2 develops java code in Component_A in Dev_Stream1; Dev1 & Dev2 are implementing a feature together. Estimated effort is 2 man-weeks.
Dev3 & Dev4 develops java code in Component_B in Dev_Stream2; binary of both components are jar file.
Developers manually deliver the change sets to the Integration Stream. Integration Stream builds a war file. Integration Stream can be configured for CI where Build will be triggered every 5 minutes.
Lowest level Stream is the Dev Stream, where Dev1 & Dev2 exchange their code. All deliveries to Dev Stream would not be buildable; build will succeed in Dev Stream only when the feature is completely developed.
How to implement CI to Dev Stream. Should the work break down be planned in such a way that daily Deliver of Dev1 & Dev2 will still build ?
One answer

I think that the setup of a development stream that not builds is the first fundamental issue in the whole set up.
Not only should daily delivers build, but the development build should build.
I don't see what work breakdown (usually I would use this as how the work items are organized in hierarchies) has anything to do with the stream hierarchy.
In general continuous integration to me means that you build and test often and not being able to build and test is a no no.
Comments

Yes. by work breakdown, I mean work items, its schedules & its assignments. Daily builds in Development Stream should break, for the developer to identify the conflicts early.

For a build to break, the build has to be buildable and executable. You say your buids are not designed that way:
"All deliveries to Dev Stream would not be buildable; build will succeed in Dev Stream only when the feature is completely developed."
I think this is a fundamental problem and should be fixed.