I am not a tax guru but believe you need to revisit what the merger means. The cost basis will be adjusted downward based on the dividend portion that was considered a return on capital and not return of capital for IRS purposes. Then, the conversion factor will be applied at current market prices to determine both the sale price for taxable purposes and your new cost basis for the TGRP shares (which you now have to hold 1-year for long term capital gain treatment. Since I bought all my NGLS ranging from $35-40 I will reflect a significant loss carry forward. Remember they are leaving the MLP structure (treated differently than C-shares) for C-shares.
If you believe that a retail investor has the pull to defeat this you are silly. The institutional investors control the outcome. All in all, this will work out for everyone if we get a recovery in natural gas/oil prices during 2016.