Vent fan ducting

[DIYspanner]

I have a bathroom and an en-suite.

Can I install inline vent fans and vent the air through one roof mounted vent if I install one way flap valves in the ducting?

Also, since I need a condensation trap for the vertical run up to the roof vent, does it comply with building regs if I run the condensation off down into a shower cubicle or bath?

Thanks