I assume you're using the I2CREAD and I2CWRITE commands in PBP?
When each PIC is done reading/writing the EEPROM, add some code to manually set those pins back to INPUTs (input sda, input scl) immediately after the read or write. With the pins set as inputs, it would be as if they weren't even there. I think about the only thing you'd have to worry about would be read/write collisions.