  Some of the high Tc iron pnictides contain magnetic rare-earth elements,
raising the question of how the existence and tunability of a d-electron
antiferromagnetic order influences the heavy fermion behavior of the f-moments.
With CeOFeP and CeOFeAs in mind as prototypes, we derive an extended Anderson
lattice model appropriate for these quaternary systems. We show that the Kondo
screening of the f-moments are efficiently suppressed by the d-electron
ordering. We also argue that, inside the d-electron ordered state (as in
CeOFeAs), the f-moments provide a rare realization of a quantum frustrated
magnet with competing J1-J2-J3 interactions in an effective square lattice.
Implications for the heavy fermion physics in broader contexts are also
discussed.
