Michael,
After an offline conversation, I was emailed a drawing with phantom parcels, where the user reported similar issue using 2014 SP2.
I've personally tested their drawing, using 2014 SP2 and can confirm the failure now being reported (a failure that I did not experience previously)... The vl-Catch-All-Apply call is precluding the following error from being reported, when the Remove() Method is invoked on the oSites Object:
Civil 3D API: The parameter is incorrect.
I've verified that the API allows for either Name (string), Object reference as parameter for the Remove() Method (and have tried both variations), yet the call throws an exception nonetheless.
I've been exploring a .NET alternative, but do not have anything more conclusive to add at this time.