If you have multiple company accounts and you want to display all Jobs from other accounts in one account's Careers Site, this is easily done.
Click "Careers Site" on the top menu of the company account that you want to display Jobs from other accounts on > Go to your Careers Site.
On the left side of your Careers Site, click “Careers Site editor.”
Click the "+" button below the content sections to go to "Custom HTML/CSS". You can reorder the "Custom HTML/CSS" module to position your Jobs at a nice part of your Careers Site.
Add the following code to the "HTML" field and Save.
The next step is to add this code to the "Scripts in header" field.
Edit the "COMPANY_ID" in the JS script to the IDs of all the company accounts whose Jobs you want to show.
To see these IDs, go to "Settings" on the left menu > "Apps and Plugins" > "Jobs widget" > Under the "Settings" tab, check all the company accounts whose Jobs you want to show.
Go to the "Code (Sync)" or "Code (Async)" tab and look for the numbers in "companies". Those are the IDs of the company accounts you selected.
Copy those numbers and paste them to "COMPANY_ID" in your "Scripts in header" form and hit Save.
You should then see all Jobs from the company accounts you selected listed in one Careers Site now.