Thanks Dale, I assumed this was the case but wasnt sure if I was just overlooking it or maybe it had some different verbage from the rhinocommon.
For what its worth it seems you can add a new object to the doc and assign a new objectattributes to it and that works however the object addition is very strongly typed so you have to create a huge switch or elseif to track deleting and reading objects to the files object table. a simple GeometryBase.Add(geobase, objectattributes) could be a huge help for me here vs .AddBrep() .AddSurface() .AddMesh() and so on!