In real world, there is wire resistance, but many times this can be ignored (especially in low current systems). One meter of copper wire with D=0.5mm has a resistance of about 0.1 Ohms. If you would insert a 0.1 Ohms resistor between nodes AB and AC, you will notice negigible difference. To save time, you may put the problem into a spice simulator. You can model your controlled current source with the Voltage Controlled Current Source in Pspice.
Other sign for virtually no influence is calculating the voltage drop across the inserted resistors based on your calculated currents. Generally spoken, if the resistance of the connecting wires in a series circuit is very low with respect to the total resistance in the series circuit, the wire resistance can be ignored in simple ballpark calculations. But be careful in practical circumstances...
In a 12V car electrical system, thick wires are used, especially for the starter. It can draw more then 200A from the car's battery. If you allow a voltage drop of <0.5V, the wire resistance should be less then 0.5/200 = 2.5 mOhms. A 1m long wire with D= 3mm has about 2.5 mOhms of resistance. The wire will dissipate 200A*0.5V = 100W during starting!
You can imagine that with this dissipation the wire's insulation will melt, therefore the actual cable from battery to starter is very thick.