I don't fully see the problem.
If you want to use the internal effects for the monitors, connect the EFX SEND into a free channel.
Adjust how much effected signal you want to send to the monitor mix by adjusting the monitor send on that channel. Adjust how much you want on the main mix with the fader on that channel.
Make sure to keep the EFX aux on that channel at -? or it will create a feedback loop..
The EFX SEND on the PV14 is used for sending the dry signal to an external effects unit, it taps the signal directly before the internal effects generator. It is essentially a post fader aux send...