That is not a problem. All you need do is ensure there is no pin clash. SD usually demands pin4 to select and pin 10 set to output also uses the SPI bus pins 11,12,13. RTC uses pins A4,A5. Many LCDs use the same bus as the RTC and share the pins. Others can go anywhere but conventionally use a few digital pins, like 5,6,7,8,9. What you want to do is common practice. Even if there is an initial problem, it is easily fixed.