var pdfDocsOnlyUser = documentSource.SiuSetDocumentInfoDocuments
                    .Where(p => new[] { "UserDocument"}.Contains(p.DocumentType, StringComparer.InvariantCultureIgnoreCase));

 var FsDoc =  documentSource.SiuSetDocumentInfoDocuments
                    .Where(p => new[] { "RecordingDoc", "Miscellaneous" }.Contains(p.DocumentType, StringComparer.InvariantCultureIgnoreCase)).OrderByDescending(p => p.ProcessingState).DistinctOn(p=>p.ParentDocumentId).FirstOrDefault();