This would probably be parity for a portfolio manager at the moment, however, a newly minted 15 year mortgage might have slightly longer duration than the MBS portfolio and therefore a greater MTM discount.

There are people who are renting in my community and apparently there's a daycare diagonal from me lol.

Already the cost of producing solar is equal or better than coal and is fast approaching parity with other energy sources.

Would I be better of just sticking with my brokerage account if the returns or more on parity with the stock market but much less liquidity?

Although if you know principal of measuring the 2 diagonals of a space, you can see how close or far from square your space is.  

are they all at parity? 

They cut the corner diagonally to hide the seam.

Let them see that the the seller financing can be a win for all parities when looking at three different options.

Below is a map that shows the difference in zones the floodway has diagonal lines and is usually labeled as a floodway. 

There's a way around it, but it's highly complex and therefore not recommended.This is not a bad result for him, because he essentially gets to deduct half of your interest.What is bad is that achieving economic parity between the two of you in such arrangement is extremely convoluted.