I'm finding it somewhat difficult to understand the question. I'll take my best shot at it anyway. If your question is:
Is it possible to have a BitsyXb personality board with an ethernet chip present plus some other chip and have them share the bus?
Then the answer is:
Yes, it makes things much more complex, but it is possible. An example of this is our Quad UART Personality board that has both a UART and a Ethernet chip. To make this possible a CPLD was used on the personality board to decode addresses and provide chip selects.
Note that the bus provided to the Personality board is a PCMCIA bus from the PXA processor. It would be quite difficult, if not impossible, to use the bus as both a PCMCIA (or CF) slot and also support an ethernet chip. This is because a PCMCIA slot would require the whole address space on the bus with no addresses left over for other devices.