Thank you yuhuisg, for your help. I've understood we're allowed to add one dimension item only..I'll try to use another pane for additional item.

Guessing from GUI, it seems to be possible, but after dropped multi items as below, the result didn't show multi items in the center node. What I want: To check flow(both entry, exit) of several URLs in single pane.Thank you very much for reading, it'd be grad if you will help me.