Running short of GND port in Arduino Mega 2560


I am using an arduino mega 2560 for my project.

I have 2 heavy motors(30 amps), 1 bluetooth unit, and 3 stepper motors(2 amps). I have in total 6 GND wires to be connected and Ardunio Mega 2560 has 4 GND ports. So I am short by 2. Can I connect 2 or more GND wires into 1 GND port in Arduino or that is a strict NO. if not what is the alternate solution.

Thanks in advance!!

Yes, you can combine several signal ground wires to one ground pin.
Can’t run motor current wires over the Mega ground pins though.
You might need a star grounding system for those big currents.
Post a diagram if you’re not sure.

Attached is the circuit diagram…I tried running both the motors together, attached to the arduino and they work fine. I can probably combine GND wires for S3 and S2 into one GND port and for S1 and the Bluetooth unit into one GND port. Does that seem like would work?

Yes that looks fine.

Why the (unknown) BT module on pin 1 and 2 ?
Pin 1 is used by the USB<>serial chip.
A Mega has three other hardware serial pins.