Lots to consider here depending on date purchased, how it was split, what is being built, and when it is placed into service.

Quote from @Richi Brown: Well done.I'm curious to know why you would consider OOS STR when the in-state MTR was a failure?

Just my two cents as I have considered it as well. 

Here are some other important 45-Day rules to consider: - If your parents cross the 45-Day threshold with identified properties, but subsequently fail to buy them, they cannot get their money back until Day 181 when their exchange is complete. 

Consider a lending partner thats invested in your success, offering coaching and consultation to mitigate risks and foster mutual growth, which ultimately makes the loan less risky for all parties involved.

I’d like to start looking at deals in Suffolk to consider (for buy and hold rentals).

I'd consider utilizing the tax experts option on turbo tax if you have any specific filing questions.

Have you considered doing a 5% down owner occupy loan? 

Considering your situation, holding onto your current duplex with its strong cash flow and exploring refinancing later when market conditions are more favorable and you have built up more equity seems advisable.

Every market is different but there are things to consider (my first job out of college was bidding on properties at the courthouse steps):1.