Dual Employee

Assume a tax-exempt entity, "Parent," has a for-profit subsidiary, "Sub."  One of the executives of Sub is also an officer of Parent.  As an officer, he would (at least typically) be considered an employee of Parent.  Assuming the plan language permits it, any issue with him participating in 457(b) and 457(f) plans of Parent?

Presumably, any 457(b) deferrals should be limited to his compensation received from Parent for his officer duties.  

Any limits to what he can get on the 457(f) side?  It seems like this might have 4958 or 4960 implications.