Yes, that's OK but remember that you only have 4 free segments in Europe (and you can't buy more in the continent of origin), so this imposes two further constraints:
- you have to go intercontinental from DXB (which means CX to HKG) (or do an open jaw and a separate ticket back from DXB to another intercontinental gateway)
- you would need to fly back to DUB on a direct intercontinental flight, which means one of the EI flights from the US