Thanks for the reply-

Client does have other self-employment income which we report on Schedule C - he is an Investment Manager for several clients.

He is/has been a general partner in a few other partnerships over the last 20 years. In some cases, he is paid an annual management fee, reported to him on K-1 on Line 4a - Guaranteed Payments for Services and on Line 14, Code A, as self-employment income.  

Those amounts flow to Schedule SE, where it is combined with other self-employment income/loss to arrive at self-employment tax.    

Those management fees are self-employment income and if he were paid a fee by this partnership, the same would be true.  I guess that's the relationship.   

The instructions for Form 4952, p3, Part III, Line 8 state, after saying it goes to Sched A or E, adds, "Also, if any part of the interest is attributable to a trade or business that isn't a passive activity, enter that part on the schedule where you report other expenses for that trade or business".   The only other income or expense there's ever been from this partnership is a bit of interest income.  

As I write all this, it's becoming clearer to me why my thought doesn't fly.  I appreciate your assistance as I suss this out.