Hi Hugo,

Thank you for posting in our forums! Yes, it is possible to have Multi-column headers in Hierarchical Grid on every level no matter if you have load on demand or not. What you have to do is to create a GridColumn object and add the data column definitions in its Group collection. Then you add this object to the Columns collection of the layout model object. Also you need to add the MultiColumnHeaders feature to the grid’s definition in order this to  work. You can review the code snippets below:

Creating Multi-column headers in child layout.

GridColumnLayoutModel layout = new GridColumnLayoutModel();
layout.Columns = new List<GridColumn>();

GridColumn group = new GridColumn();
group.HeaderText = "child group";
group.Group = new List<GridColumn>();

layout.Columns.Add(new GridColumn("Developer Id", "DeveloperId", "number", "100px"));
group.Group.Add(new GridColumn("Project Id", "ProjectId", "number", "100px"));
group.Group.Add(new GridColumn("Name", "Name", "string", "150px"));
layout.Columns.Add(group);
layout.Columns.Add(new GridColumn("Position", "Position", "string", "100px"));
layout.Columns.Add(new GridColumn("Hire Date", "HireDate", "date", "120px"));
layout.Columns.Add(new GridColumn("Salary", "Salary", "number", "120px"));

Creating Multi-column headers in root layout.

GridModel gridModel = new GridModel();
gridModel.Columns = new List<GridColumn>();
GridColumn group = new GridColumn();

group.HeaderText = "group";
group.Group = new List<GridColumn>();
group.Group.Add(new GridColumn("Project Id", "ProjectId", "number", "100px"));
group.Group.Add(new GridColumn("Name", "Name", "string", "200px"));

gridModel.Columns.Add(group);
gridModel.Columns.Add(new GridColumn("Start Date", "StartDate", "date", "160px"));
gridModel.Columns.Add(new GridColumn("End Date", "EndDate", "date", "160px"));
gridModel.Columns.Add(new GridColumn("Is Postponed", "IsPostponed", "bool", "110px"));

// add the MultiColumnHeaders feature
gridModel.Features.Add(new GridMultiColumnHeaders() { Inherit = true });