Click a block in the tree, hold down the mouse, and drag it to another block and release.This will set the dragged block as a downstream block from the one that you dropped it on.
Blocks in the tree are visually grouped if every block in the group has the same set of
upstream blocks.When a group is visually formed, you can drag-and-drop the entire group onto another block
and the entire group will be set as the downstream for the block you dropped it on.
Hover your mouse over a block to reveal 2 orbs (aka circles, dots, etc.).
Click and hold down on the top orb and drag it to another block then release.
This will set the 1st block as the downstream dependency of the 2nd block.If you click on the bottom orb, then the 1st block will be set as the upstream dependency of the 2nd block.