Hi Abhay,
You'll need to look at the ADS1259EVM User's Guide to determine the necessary jumper settings. I don't think you have to make any changes, but you will need to decide if you are controlling the ADS1259 directly, or through the PGA280 using its extended chip select mode.
Regarding the MMB0 interfering with SPI communication, I think it is safest to assume that it will interfere. You could de-solder J7B from the ADS1259 (removing the digital connections between the MMB0 and ADS1259EVM), and only use the MMB0 to power the ADS1259EVM; however, you would still need to short the LaunchPad and the MMB0 grounds to make sure the ground reference voltages are the same.
Best Regards,
Chris