Donald Trump just announced that he tested positive for COVID-19. If he is still contagious during on Thursday, October 15th, what are the options for the 2nd Presidential Debate? Can someone else like Pence or Kayleigh McEnany stand in for him? Is that even a possibility? Can it be done remotely?
Debates are not constitutionally mandated. There is no law that requires a particular number or format of debates.
So it a matter for the TV networks, Trump and Biden to agree. The easiest option is to postpone. It is perfectly legal for Pence to appear in place of Trump, or to debate in separate places by video conference. It is legal for the Press Secretary to appear, but that would be a very odd choice (she isn't a particularly senior member of the Trump team)