Correct; the I-751s were submitted while they were in the home country.
The latest I-751 case status for both of them shows to be "Case Was Received and A Receipt Notice Was Sent".
Great point about uploading more evidence once we are back in the USA.
Shall the new evidence consist of - residence proof in USA, more pictures, employment in the USA proof etc?
Also I hope as long as the I-751 case status is "under process" we shall be okay entering into the USA next month at the port of entry ...?