Investors & landlords

Method 2 looks closest.  The best way to think about this is as two separate transactions:

1. You sold all shares of Macquarie.  You'd report the Cap Gain as appropriate.
2. A minute later, you purchased 100 shares of the new MLP.

For 1, your cost basis is the $3,138 you calculated.  Your proceeds are $3,560+the value of the 100 shares.  While closing price on the first day of trading is likely close to the correct value for the shares, the partnership should be able to tell you the exact value to use.  You may even be able to use the opening K-1 they provided: in Part II, Section L, "Beginning Capital Account" should be 0, and the next line will show "Capital contributed".  "Capital contributed" is likely the value of the 100 shares.  But again, the partnership should confirm.  There may be info on how to contact them on the K-1.  Otherwise, you could contact them directly (e.g., through Investor Relations).

Once you have the correct basis, you may want to have your broker update the basis they show.  But this is optional since MLP's are "non-covered" and the broker's basis isn't considered accurate.