You could combine them, but you will have to be careful how you do it. Some ways will work, some will not. Just go with what sounds good.
In the key of C, you will have C major, F major and G major. The D chord will be minor. Maybe as you are just beginning to expirement, try playing the C major pent over C,F and G chords. Try also, using the F major pent scale over the F chord and the G major pent scale over the G chord. And, try using the d minor pent scale over the d minor chord.
The most important thing is to let your ear decide what sounds good. Sometimes, as you get better with one scale, you find ways of just using the one scale in better sounding ways.

Good luck,
Michael