mass-resolved OB-LF sibling boost B(m) = phi_OB_mod / phi_prim:
      m  phi_prim  siblings   B(m)
    8.4     125.0    1083.2   9.67
    9.3     118.0     937.9   8.95
   10.2     102.0     813.2   8.97
   11.3     104.0     704.0   7.77
   12.4      87.0     607.8   7.99
   13.7     125.0     522.3   5.18
   15.1      85.0     446.4   6.25
   16.6     103.0     381.1   4.70
   18.4      72.0     324.6   5.51
   20.2      53.0     277.7   6.24
   22.3      48.0     238.0   5.96
   24.6      33.0     204.6   7.20
   27.1      27.0     176.4   7.53
   29.9      28.0     151.6   6.41
   33.0      21.0     130.2   7.20
   36.4      12.0     112.5  10.38
   40.1       6.0      97.6  17.26
   44.2       7.0      85.2  13.18
   48.8       6.0      74.1  13.35
   53.8       1.0      64.6  65.61
   59.3       7.0      56.2   9.03
   65.4       2.0      48.7  25.35
   79.5     103.0      17.8   1.17
   87.6       1.0      14.6  15.62
   96.6       1.0      12.6  13.60
  106.6       2.0      10.6   6.28
  129.6       1.0       7.4   8.45
  142.8       2.0       4.3   3.15

OB mass-function slope (dlog phi/dlog m):
  baseline (primaries=OB) : -1.83
  modified (+ODF siblings): -1.78
  steepening d(slope)     : +0.05

  implied increase in Dbeta=(alpha+delta)/gamma : -0.03  (gamma=1.8)
  => increase in alpha ~ gamma*dDbeta = -0.05
     (baseline alpha=0.5 -> ~0.45); tau0 rises with alpha along the P&G degeneracy