I created a component which has replicants in it. I kept default content without adding any replicant.
Now I used the component to create a page(this page has layout and template). I entered the my related content and added few more replicants. I had to change the component and add one more datum to it. I added the datum and updated component and template too. When I open the page and click on update. The default content from the components gets appended to the existing content.
OS: Windows
Teamsite Version: 7.4.1