Are moonlets hidden among the clumps in Saturn's innermost ring?

Saturn's D68 ringlet is the rings' innermost narrow feature. Four clumps that appeared in D68 in 2014-15 remained evenly spaced about 30 degrees apart and moved very slowly relative to each other (Hedman 2019, Icarus), which is reminiscent of the stationary configurations of co-orbital nearly equal-mass satellites (Salo & Yoder 1988, A&A). We therefore explore the possibility that the source bodies for these four clumps are in such a co-orbital configuration. The spacing between the clumps is somewhat smaller than one would expect for a configuration of four moons, and changing the mass ratios is unable to fix this. We therefore consider whether an unseen fifth object could account for the discrepancies in the angular separations and allow the system to reach stationarity (Renner & Sicardy 2004, CMDA). We find a range of possible longitudes where a fifth co-orbital object could be, as well as the mass ratios between the five objects for any specified longitude within these ranges.