cs
            var editor = _propertyEditorCollection.First(x => x.Alias == "Umbraco.BlockGrid");
            var grid = _dataTypeService.GetDataType(Guid.Parse("9490ca3c-7a5e-4be3-aa73-712136b2a5a1"));

            var existingblocks = ((BlockGridConfiguration)grid.Configuration).Blocks.ToList();
            //add the new blocks
            existingblocks.AddRange(blocks);

            ((BlockGridConfiguration)grid.Configuration).Blocks = existingblocks.ToArray();

            var newDataType = new DataType(editor, _configurationEditorJsonSerializer)
            {
                Name = grid.Name,
                Configuration = (BlockGridConfiguration)grid.Configuration,
                ParentId = grid.ParentId,
                Key = grid.Key,
                Id = grid.Id,
            };

            _dataTypeService.Save(newDataType);