Update the grid changes from other form

simply create a property which will spose gridview datsource as
public DataTable dtCustomers
{
        get
        {
                return (DataTable)datagridview1.datasource;
        }
        set
        {
                datagridview1.datasource=value;
        }
}
.
.
.
.
in secondayfrom create a property like this
public MainFrom m
{get;set;}

in Main form when  u open seconday from
SecondayFrom f=new SecondayrForm();
f.m=this;
f.show();


Now in seconday from you can access main form..
Simply make changes to m. dtCustomers after save in secondayfrom, it will refresh the grid automatically.

Check this is correct answer if it helped,