@rksteeves the Swan is connected to the Notecard (internally) via the I2C bus, which is the same physical I2C bus that is connected through to the QWIIC connector. It sounds like you are configuring the Swan to be an I2C Master when you run the notecard.begin(0x17) function and thus the Swan is no longer listening for I2C commands from the Wemos (as it previously did in Slave mode).
My suggestion would be to use Serial (UART) to communicate between the Swan and the Notecard (like this user is doing), allowing you to keep the Swan as an I2C Slave. You will need a physical connection (e.g. three jumper wire) between the N_RX-F_TX and N_TX-F_RX pins as well as GND.
Alternatively, if you want to do everything over I2C, you will need to use a different set of I2C pins for the Wemos (not the QWIIC connector) that are not connected on the same I2C bus as the Notecard. Your architecture would then look like:
Wemos (Master I2C_BUS_0)
Swan (Slave to Wemos I2C_BUS_0, Master to Notecard I2C_BUS_1)
Notecard (Slave I2C_BUS_1)
If you’d like me to provide you with more information on how to set up multiple I2C buses, let me know!
Alex