Click the 'Jobs' icon in the menu and go to the 'Calendar view' tab. Here you'll be able to choose a job for which you would like to set up a splitting invoice.
Make sure that both contacts (a tenant and owner) are linked to the same pool.
Create a job for this pool and go the "Job details" page. Add the desired products to the Invoice section and scroll down. Choose the "Preview & Send invoice" option and hit the "Submit" button.
Preview invoice page
Move to the "Preview invoice" page and scroll to the "INVOICE TO" section. Click on the "Select contact" and choose the second contact.
Hit on the "Add selected recipient" button. There are 2 contacts in the "INVOICE TO" section.
Scroll down to the "INVOICE" section. Here you can choose which particular contact will pay for selected invoice items.
In the "Summary" section, you can set up an email message for each contact.
Click on the "Send" button and each contact will receive a separate invoice with particular invoice items.