What happens if you buy the duplex with a conventional loan with the purpose to build an ADU to move in shortly afterwards?

I use Monarch for personal purposes, they use 3 aggregators, and I've had no problems staying connected to all my accounts. 

As a lender (aka “Maker”) to Norada, you are a valued member of the Norada family.The purpose of this correspondence is to provide you with an update on the repayment under the terms of the promissory note (“Note”) as an obligation of Norada Capital Management, LLC (“Norada”).As with all businesses, Norada is subject to market factors that could impact its ability to make payments.

I think I would probably talk to an attorney tbh these business purpose non regulated loans do not have rate locks that have to be honored legally.. they can and do change them unilaterally.. borrower accepts counters or declines and loan fails. 

I wrote the above for informational purposes.

DSCR loans are widely available to first time investors, but they are considered business purpose loans and you will be required to sign documents stating that neither you nor any family member will occupy the property as your or their primary residence as long as that loan is in place. 

So you'll have to deal with that.Some will be wanting to finance for tax purposes.

Where did you read about doing that and for what purpose?

DSCR will not work as they are business-purpose loans and you will have to sign an affidavit of commercial use. 

The agreement stipulates:"The owners agree, that no water shall be used for commercial purpose, but only for their private domestic use including vegetable gardens and livestock maintenance."