Binding sharepoint groups with ADLDS

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SharePoint

Hi friends,

I have a scenario, where I am using Silent sign in from ASP.NET application to sharepoint application using Form Authentication.
I have successfully acheived this.

But the problem which I am facing is that ,when I create any users for my asp.net application ,I have to add the same users to my Sharepoint Extended [extranet ]Application ?

Is there any way to add[OR BIND] the groups from ADLDS TO Sharepoint application ,where we dont need to again add the same users to the sharepoint application[instead it gets added to the sharepoint application by default.]?