I am struggling to understand the best way to say that I have done for a couple of days the work tasks of the Company owner. So far I have find these solutions:
I have covered for the Company owner, during a few days at the exhibition in New York.
I have stood in for the Company owner, during a few days at the exhibition in New York.
I have substituted for the Company owner, during a few days at the exhibition in New York.
Is there a more formal phrases I can use?