Destiantion different from origin but via origin city

Hi, In relation to the above, if I:
- flew Dublin to Abu Dhabi with Etihad
- stayed there for a few days
- flew on with Etihad to say, Chengdu or Beijing and stayed there for 72 hours
- flew back to Dublin via Abu Dhabi with Etihad, not staying in Abu Dhabi on the way back

would I be eligible for the 72 hour free transit? Technically my origin city into Chengdu would be Abu Dhabi and my destination would be Dublin.
Interested to see could this be done for free.

Thanks for your help!

Brian, Ireland.