Can I add dependencies after using catkin_create_pkg?

edit

I used first

catkin_init_workspace

and thereafter

catking_create_pkg example1 roscpp rospy std_msgs

and building a simple example file works flawlessly.

Now if I run

catkin_create_pkg example2

without specifying dependencies, it doesn't work, even though I edited the package.xml and imported exactly the same source code. The reason I want to do this, is I need to move some source code from Fuerte to Hydro, and I'd rather just copy the <build_depend> tags from one xml file to the other. But it doens't work.