Hello,

I have been looking into your post and you can achieve the desired functionality using ‘ItemFilter’ like e.g. :

            ItemsFilter filter = new ItemsFilter();

            filter.ObjectTypedInfo = new CachedTypedInfo()

            {

                CachedType = typeof(Product)

            };

            filter.Conditions.LogicalOperator = LogicalOperator.Or;

            filter.Conditions.Add(new ComparisonCondition()

            {

                Operator = ComparisonOperator.Contains,

                FilterValue = ""

            });

            this.multiCombo.CustomItemsFilter = filter;

For more information regarding how to use the XamMultiComboEditor, you can look through the following link from our online documentation :

http://help.infragistics.com/NetAdvantage/WPF/2013.1/CLR4.0/?page=xamMultiCCE_Using.html

Let me know, if you need any further assistance on this matter.