Two RSS feeds of Domain and Sub Domain for One FB Page

Hey Everyone and Authors of this plugin,

I have created a sub-domain on my main domain. There are two WP running, 1 on the main domain and 1 on the sub-domain.
Installed the plugin on both the WP installations and got to separate feed URLs.
The problem is FB allows only 1 RSS feed URL per FB page.

Can anyone please let me know how can I use both the RSS feed URLs on the same FB page. Please help its really critical.

Scenario:
Main Domain: https://www.abc.com (separate WP installation)
Sub-Domain: https://www.hindi.abc.com (separate WP installation)

2 separate RSS feed URLs ad per the above scenario

Now I want to use both the above RSS feed URLs on the single FB page

FB Page: https://www.facebook.com/abc

But in FB instant article setting only 1 RSS feed URL is permitted

Thanks