Hi,
Thank you for your interest in Syncfusion Products.
When ever an item is added to the AutoComplete Textbox dynamically, it will be automatically added to the list the next time the sugession is shown since a callback to the datasource is done. I have created a simple sample to test this and it can be founud in the sample below.
http://files.syncfusion.com/samples/Tools.Web/7.3.0.20/F90706/Main.htm Kindly view the above sample and please let me know if this helps. Also let me know if i have misunderstood your query.
Regards,
Lakxman Kumar C