Some problems of the package blockdiagram

[BIT-Octopus]

First of all, thanks for developing the blockdiagram package used in LateX.I use it to draw some control system diagram. However, I encounter some problems, so I want to ask for your help. When I want a branch from a line connecting A block and B block to connect C block, it can only connect correctly when C is below A and B. When C is over them, the branch line cannot connect to the main line.It left a gap. What's more, I can't arrange the order of a lot of lines (yxylink) according to my mind. I will appreciate it if you take time on it.
example.zip