If you connect the collector of the BC547B to ground, it will be automatically connected to the ground pin of the ULN2003. The schematic may not show it, but the netlist and layout will.
You can edit the Hidden Pins property of the ULN2003,and let GND(Pin8) connect to another net(e.g. 547_C),then you should add 547_C to power rail list(Design--Power rail).Now put net lable 547_C on the BC547's collector.
Try it,you'll find Pin8 of ULN2003 only connect to collector of theBC547.