We've been happy with the service (tried a few similar services in years past that gave users with different devices various errors and complications, nice to see someone getting it right). 

Use Microsoft Onenote, you can create notebooks 9 maybe name it " Properties", in the notebook create a tab for each property, then you can have different pages for each tab, you can make one page " Receipts" for that property. you take a picture, save it to the page for whatever property in one note, with the APP on your phone. you can save them directly to that page, create Receipts pages for each property. and you can retrieve that information on any device that has Onenote. you can even name each page by the year if you want " receipts 2018" and you will always have your records anywhere you go.

I currently live in Connecticut and work as a medical device representative.

Something to keep in mind as well is most people that are not tech savy as soon as "something" goes wrong with their devices they will blame it on "the internet" or "the WiFi".I would not advise going this route unless you have some experience in IT and don't mind supporting it.

Conventional loans are governed by Fannie Mae and Freddie Mac (if you have heard those names before).  

I missed the line that that is the reason as to why portfolio lenders exist, for those who have exhausted the their Freddie Mac & Fannie Mae loans. 

Easy to google up Fannie Mae guidelinesFreddie Mac has Home Possible with less down, but other restrictions. 

The device doesn't have to be super accurate, it only needs to show that Unit A used x portion and Unit B used y portion.

changes only affect freddie mac as far as I know not fannie mae is still the same. its 6 financed properties for freddie but they dont seem to have a limit at 4 for cash out like fannie.

If the funds are in your brother's account for more than 60 days then Fannie Mae and Freddie Mac don't care.