Hi,
1) There is no easy way to do this, if there is ever any, depends on used shift, duty cycle, its update need and mode used. If the shifting is done within a PWM period there is no issue with OPWMB mode for sure. For the case when crossing boundary it cannot work for sure. One way could be changing the polarity and recalculate match values. Most probably this will bring some SW overhead and possible glitches on polarity changes, I guess. Another way could be using an DAOC mode and update A and B registers (thus re-enable comparators) with the help of DMA, for example.
If the phase shift is not changing you can use OPWFMB mode and init the CTN register by shifted value when PWM generators are disabled, as mentioned in https://community.nxp.com/thread/449233.
But for phase shift change the PWM must be stopped then.
2) there is no synchronization between module counters in terms the counter will be reinit at other channel match/capture or similar. Counters can be just started at the same time using global prescaler
BR, Petr
