Issue when writing XML data to a datatable / gridview

I have an API feed from a Web Services call with our LMS, condensed sample code is below. <a:RosterAddedUserView> is duplicated for each user that appears on the roster and <a:PartAttendanceView> is duplicated for each piece of the course schedule (Day 1, Day 2, etc.).

<applicationApi xmlns:i="http://www.w3.org/2001/XMLSchema-instance"><Validations /><status>200</status><timeStamp>2017-04-26T17:03:11+0000</timeStamp><totalRecords>1</totalRecords><data xmlns:a="www.applicationurl.com/Services"><a:SessionRosterResponseView><a:Roster><a:TotalSeat>20</a:TotalSeat><a:TotalSeatAvaliable>4</a:TotalSeatAvaliable><a:PendingUser /><a:AddedUser><a:RosterAddedUserView><a:UserId>12345</a:UserId><a:UserFullName>Smith, John</a:UserFullName><a:OUs><a:OrganizationUnitView><a:Name>EMPLOYEE</a:Name><a:TypeName>Division</a:TypeName><a:RelatedOUs i:nil="true" /></a:OrganizationUnitView></a:OUs><a:Locator>LocNum</a:Locator><a:Attendance><a:PartAttendanceView><a:PartName>FirstDay</a:PartName><a:UserAttendance>true</a:UserAttendance></a:PartAttendanceView><a:PartAttendanceView><a:PartName>SecondDay</a:PartName><a:UserAttendance>true</a:UserAttendance></a:PartAttendanceView><a:PartAttendanceView><a:PartName>LastDay</a:PartName><a:UserAttendance>false</a:UserAttendance></a:PartAttendanceView></a:Attendance><a:Score i:nil="true" /><a:Passed>true</a:Passed><a:Status>Incomplete</a:Status><a:SessionCompletionDate>4/14/2017</a:SessionCompletionDate></a:RosterAddedUserView><a:RosterAddedUserView><a:UserId>67890</a:UserId><a:UserFullName>Doe, Jane</a:UserFullName><a:OUs><a:OrganizationUnitView><a:Name>EMPLOYEE</a:Name><a:TypeName>Division</a:TypeName><a:RelatedOUs i:nil="true" /></a:OrganizationUnitView></a:OUs><a:Locator>LocNum</a:Locator><a:Attendance><a:PartAttendanceView><a:PartName>FirstDay</a:PartName><a:UserAttendance>false</a:UserAttendance></a:PartAttendanceView><a:PartAttendanceView><a:PartName>SecondDay</a:PartName><a:UserAttendance>false</a:UserAttendance></a:PartAttendanceView><a:PartAttendanceView><a:PartName>LastDay</a:PartName><a:UserAttendance>true</a:UserAttendance></a:PartAttendanceView></a:Attendance><a:Score i:nil="true" /><a:Passed>true</a:Passed><a:Status>Incomplete</a:Status><a:SessionCompletionDate>4/14/2017</a:SessionCompletionDate></a:RosterAddedUserView></a:AddedUser><a:Comments /><a:TotalPendingUsers>0</a:TotalPendingUsers><a:TotalAddedUsers>16</a:TotalAddedUsers></a:Roster><a:Result>Success</a:Result><a:Reason i:nil="true" /></a:SessionRosterResponseView></data></applicationApi>

I need to be able to generate a table view of this data including the following fields: UserID, UserFullName and attendance. I'd like the attendance to be columns with each record.

Example:

I've been able to successfully pull the UserID and UserFullName, and have been able to pull in the attendance column headings based on <a:PartName>, but when I attempt to fill with the <a:UserAttendance> value I am not getting an inaccurate result. I've attempted this a few different ways, but it appears that currently I am getting the last user's attendance record for all users.

Current Results:

Any help with troubleshooting the code would be much appreciated.  Below is the code I am using that is attached to a button on a Windows Form that populates a Data Grid View.  I am guessing I'm doing something out of place, but I can not figure out what the issue is with my code.

private void btnReadXML_Click(object sender, EventArgs e)
{
//Load XML Data and create Namespace Manager
XmlDocument xmldoc = new XmlDocument();
xmldoc.Load(@"Path_To_XML.xml");
XmlNamespaceManager nsmgr = new XmlNamespaceManager(xmldoc.NameTable);
nsmgr.AddNamespace("a", "www.applicationurl.com/Services");

//Create data table and add UserID and UserFullName columns
DataTable dt = new DataTable();
dt.Columns.Add("UserId", typeof(string));
dt.Columns.Add("UserFullName", typeof(string));

//Populate UserID and UserFullName columns
XmlNodeList userList = xmldoc.SelectNodes("/applicationApi/data/a:SessionRosterResponseView/a:Roster/a:AddedUser/*", nsmgr);
foreach (XmlNode user in userList)
{
    DataRow dtrow = dt.NewRow();
    dtrow["UserId"] = user["a:UserId"].InnerText;
    dtrow["UserFullName"] = user["a:UserFullName"].InnerText;

    //Add PartName columns for attendance records (only checks the first occurance of RosterAddedUserView - all users will have the same Parts.)
    XmlNodeList partList = xmldoc.SelectNodes("/applicationApi/data/a:SessionRosterResponseView/a:Roster/a:AddedUser/a:RosterAddedUserView[1]/a:Attendance/*", nsmgr);
    foreach (XmlNode part in partList)
    {
        if (!dt.Columns.Contains(part["a:PartName"].InnerText;))
        {
            dt.Columns.Add(part["a:PartName"].InnerText;, typeof(string));
        }
    }

    //Populate PartName columns with User Attendance values
    XmlNodeList attendList = xmldoc.SelectNodes("/applicationApi/data/a:SessionRosterResponseView/a:Roster/a:AddedUser/a:RosterAddedUserView/a:Attendance/*", nsmgr);
    foreach (XmlNode attend in attendList)
    {
        dtrow[attend["a:PartName"].InnerText] = attend["a:UserAttendance"].InnerText;
    }

//Add the created rows to the data table
    dt.Rows.Add(dtrow);
}

//Set DataSource for dataGridView1 to the data table.
dataGridView1.DataSource = dt;
}