Adding custom author details

Hello,

I accept guest articles for my blog. I am using twitter cards and when articles are shared it shows By @jijojose. I want to change it to their twitter handle.

I know its possible by creating accounts for the guest blogger, but I don’t want to create accounts for guys who just post 1-2 articles. I want to manually add their twitter handle to the post. Is it possible? Please help.

Thank you advance.