Oh my oh my,
I’ve tried the control rig solution a while ago when I wasn’t sure of what I was doing and I didn’t check the “layered” option !
So I assumed this wasn’t the way 
So much head ach could have been avoided ^^
Thank you for re-pointing me to the right direction !
I will definitely give a deeper look to your “look at” rig setting.
I was very enthusiastic about rigging and animating in Unreal ! I gave it a fair try but that wasn’t a success…
So for now ill stick to my 3D software for that part, and use an unreal modular rig for such small contextual tasks.
Thank you again, you helped me a great deal on that one !
I was about to take the path of very intricated and complicated workaround 