You can see all of these groups at the top of the FTDNA I-P37 project STR results page: https://www.familytreedna.com/public/I2aHapGroup/default.aspx?section=ycolorized
In December 2014 two people in I-PF6947 and three people in I-L672* in M26*-France ordered the Big Y test, and now the tests are completed and we have this tree:
Only two people in I-PF6947 have done Big Y, so we only have one branch which shows the 18 SNPs that they share. As soon as a third person in I-PF6947 does Big Y we will be able to add another branch to the tree. And now PF6947, Y15579 etc. have been added to the official YFull tree:
What tests should the other M26+ L672+ L160- people order? A Big Y would be useful for anyone, because we now have 5 Big Y results for comparison, Beyond that, I recommend a Y11222 test, I expect that all of these people will be Y11222+.
PF6947 is already available at FTDNA for $39. We have requested some of the new SNPs from FTDNA but have informed us that they will not add uncommon SNPs to their catalog at present. I suggest that you order the SNPs I have recommended (Y11222, Y14720, Y14722) from YSeq.net which is headed by Thomas Krahn, formerly of FTDNA. SNPs at YSeq cost $17.50 each. You will need to give a new cheek scrape sample, and there is a one time cost of approximately $5 for the sample kit and shipping.