How to do bulk update articles in WordPress backend

Hi,

We use Facebook instant articles plugin for our news website. We replaced default post author with custom taxonomy guest author. It was working fine and posting articles with our custom author before we update this plugin.

But, after update, it is taking default users as authors. We changed plugin code, tried updating few articles from WordPress dashboard and it is updating fine on Facebook articles also. But, there are more 700 articles has wrong author name and we cant update it directly from dashboard. is there any other solution to do it in plugin side? or any specific hooks available to call and update only for instant articles?

Please help