Electronic – How to signify an off board connection in Altium

altiumpcb-design

I am designing a circuit board or hat for a raspberry pi 3 with the pinout below:
Raspberry pi pinout
I have a schematic symbol that is defined just as the raspberry pi header is (pin locations/numbers/names). It has multiple ground pins, which are all connected to their respective pins on the footprint.

When I am routing the PCB:
I want to tell altium that the GND pins are all interconnected on the raspberry pi, and so they don't need to be connected on my PCB. How can I do this?

Another way to put this:
How can I tell altium that parts connected to net [GND] on my PCB need to be connected to pin 6 [GND] OR pin 9 [GND] OR pin 14 [GND], but not all of the [GND] pins?
I dont want to run traces between all of the separate ground pins on the raspberry pi header while routing, but at the moment that is the only work around I can think of.

EDIT:
I say not all grounds need to be connected together because not all of them are actually used. I wanted to do this because I wanted to be able to decide which pins were actually going to be used in the PCB design stage, and not have to swap between PCB and schematic to decide which pins to be connected.

An example:
screensot of my PCB
the ground conected to pin 30 above is not normally connected to anything when this board is in use. It is broken out for debugging purposes. Being on the edge of the board, there is no reason to try to connect it to another ground, since it is only used when the raspberry pi is in use.

Thanks to desqa, I know the name of the characteristic I was looking for- Jumper IDs – and I was able to get it working in my design.

Best Answer

I think you can do this, by using "jumper ID's".

Go to the footprint editor, open your "Rapsberry Pi" footprint, double click on one of the GND pins and in the next window set "Jumper ID" to "1" (or any other number). Do the same thing for remaining GND pads using the same number. Now you should see thin grey arcs between those pads - they are connected and you can route ground track to only one of them.