on somebody's behalf
US /ɑːn ˈsʌmbədiz bɪˈhæf/
UK /ɑːn ˈsʌmbədiz bɪˈhæf/

1.
namens, ten behoeve van
as a representative of someone else
:
•
She accepted the award on her father's behalf.
Ze nam de prijs namens haar vader in ontvangst.
•
I'm calling on behalf of my client.
Ik bel namens mijn cliënt.