I have designed and simulated a few circuits on Multisim. Usually, I order a PCB for the layout of each circuit independently. However, it is cost-effective to put multiple circuits on the same board (the cost of an additional circuit on the same board is less than the cost of a new board with the additional circuit).
How does one put together multiple independent layouts from different circuits on the same PCB in Ultiboard? Several issues arise if one simply draws all the circuits in one schematic and puts them together on the same board -- for example ground and power planes get shared, and I do not want this.