IN short you can’t do it on one brand account. you have to open a new brand. It’s not too hard to do but you wont be able to post cross brand.
Can I manage multiple Facebook pages with Zoho Social?
Sure. You can manage multiple Facebook Pages by setting them up as separate Brands in Zoho Social. Brands can help you group social media accounts for different business entities. Each Brand can include one each of the following: Facebook Page, Twitter Profile, Instagram Profile, Google+ Page, Google+ Profile and LinkedIn Company Page.