Self reference table to a recursive list\collection

Question

I currently have data in a SQL table that contains a ConfigHead table and a Config Line Table. The Config Line table is a self referencing table. My new data structure has the ConfigLines that has a collection of ConfigLines, i am trying to recursively walk through the records and add a children ConfigLines to the parent ConfigLines collection. This is what i currently have....

Here is the data structure

ConfigHead

ConfigLine

As you can see the ConfigLine table has a ParentConfigLineId which references itself. If the ParentConfigLineId is 0 then that means it's a top level item.

Here is the shape of my Data Model that i am trying to get the data in.

public class ConfigLine
{  
    public int Id { get; set; }
    public int ConfigHeadId { get; set; }
    public int ParentCongigLineId { get; set; }
    public List<ConfigLine> Children { get; set; }
}

public class ConfigHeader
{
    public int Id { get; set; }
    public List<ConfigLine> ConfigLines { get; set; }
}

At the moment i am trying to recursively walk through the Config Lines but i'm not sure how to then add it to the parent list. This is what i have so far.

public void Get(int id)
{
    //Main ConfigHeader Record
    var configHeader = new ConfigHead();

    //Get the record from the db
    var configRecord = _configRepository
                       .GetAll()
                       .Include(p => p.ConfigLines)
                       .Where(x => x.Id == id).FirstOrDefault();

    //Loop the top level config lines
    foreach (var configLine in configRecord.ConfigLines.Where(x => x.ParentConfigLineId == 0))
    {
        if (configLine.ParentConfigLineId == 0)
        {
            //Add the Top Level Config line
            var topLevel = new ConfigLine
            {
                Id = configLine.Id,
                ConfigHeadId = configLine.ConfigHeadId,
                ParentCongigLineId = configLine.ParentConfigLineId
            };

            configHeader.children.Add(topLevel);

            //Check the top level ConfigLine to see if it has any children.
            var topLevelConfigLines = configRecord.ConfigLines
                                      .Where(x => x.ParentConfigLineId == configLine.Id)
                                      .ToList();

            if (topLevelConfigLines.Any())
            {
                AddChildConfigLine(configRecord, configLine);
            }
        }
    }
}

This is my recursive method - I'm stuck on how to walk down the collection and then add them to the parent item.

private void AddChildConfigLine(ConfigRecord configRecord,
       ConfigLine configLine)
{
    //Check for any child records
    var childConfigLines = configRecord.ConfigLines.Where(x => x.ParentConfigLineId == configLine.Id);

    foreach (var childConfigLine in childConfigLines)
    {
        //How to add to the collection?
        AddChildConfigLine(configRecord, childConfigLine);
    }
}