Hello surikmteoco,

Thank you for your post!

I have been looking into your question. What I can suggest is to use the DisabledDates property of the XamCalendar. More about this property you can find on the following link from our documentation: http://help.infragistics.com/Help/Doc/WPF/2014.1/CLR4.0/html/InfragisticsWPF4.Controls.Editors.XamCalendar.v14.1~Infragistics.Controls.Editors.XamCalendar~DisabledDates.html.

I have created a small sample application for you too. In the sample application I have two DatePickers from where the user can select the range of dates that should be selected. Then on a button click I am setting this range to the XamCalendar.

Please find the attached sample application and feel free to let me know if you have any further questions on this matter.