I want to make a tree with some branches out of a curve like this simple one (I've created this with the ALT+C, convert to curve:
When I set the depth to a non zero value and set the Fill settings to full, it looks like a tree with branches. But when I change the radius on the joined point, only half of the "tree" is getting bigger/smaller. When I look inside, the problem is obvious: There are essentially two separate pieces stuck together:
What can I do to get a nicely connected mesh I can work/modify on? Is there something I do fundamentally wrong? Is it bad practice to stuck connected parts of a mesh together?

