public void AddContentAndPresentationEntity(string type, int? sortOrder, int? contentId, int? presentationId)
{
if (type.ToLower() != cContent.ToLower())
throw new Exception("This is only meant to work for content, not for list-content");
if (!sortOrder.HasValue)
sortOrder = Content.Count;
var list1 = ListWithNulls(type);
list1.Insert(sortOrder.Value, contentId);
var list2 = GetPresentationIdWithSameLengthAsContent();
list2.Insert(sortOrder.Value, presentationId);
SaveChangedLists(PrepareSavePackage(cContent, list1, PrepareSavePackage(cPresentation, list2)));
}