At least from a conceptual level, these two disorders don't conflict. The effect of sleep paralysis is being conscious while having the inability to consciously direct motor functions. Sleepwalking is the unconscious direction of motor functions. So combining the two, the effect would be that you are consciously aware of yourself and your surroundings while you are also unconsciously moving about, outside of your conscious control.
Therefore the only way the two wouldn't be possible together is if their activation conditions were mutually exclusive.
Sleepwalking occurs during slow-wave sleep (N3) of non-rapid eye movement sleep (NREM sleep) cycles. It typically occurs within the first third of the night when slow-wave sleep is most prominent. Usually, it will occur once in a night, if at all.
The first of these stems from the understanding that sleep paralysis is a parasomnia resulting from dysfunctional overlap of the REM and waking stages of sleep.
So from a small amount of searching it seems it is not possible, unless SWS, REM, and the waking stages of sleep can all be overlapped.