It might be great to have the ability to include in the invoice some data which are displayed in the client card (such as the the client adress and some custom field (for instance insurance number)).
This is actually already an option - if you reach out to the guys over at support they will be able to help you get this setup.
I checked it with Nikita and here is her answer regarding the custom fields : “As per adding custom fields, this is limited. You can only add what is already in the Setup > Settings > Invoice Templates > Edit Invoice Template > Activities”
However the adress of the client is effectivelly already availbale.