Hi Ranju,
Thank you for your update.
When using MDI child, we can set the Icon of the MDI Child Form to avoid the default icon. Please find the code snippet illustrating this:
Icon ic = new Icon(@"..\..\App.ico");
this.Icon = ic;
Please find the simple sample in the following link:
http://websamples.syncfusion.com/samples/Tools.Windows/F72518/main.htmPlease try this and let me know if this helps you.
Regards,
Fathima