Hide/show/group columns in multirow header

How to hide/show columns in multirow header? setColumnHidden does not work properly.
How to group several but not all columns in the second line of multi row ? For example first header row is ‘Customer’ and the second ‘birthday’, ‘first name’ and ‘last name’. I would like to group ‘first name’ and ‘last name’ so when columns collapsed I see only ‘birthday’ and ‘first name’ .

Unfortunatley such feature is available with the custom fix only.
Please, visit sales[at]dhtmlx.com to get the details of the available customization.