Custom map: show groups seperatly

Hi,
We have a PRTG-installation for monitoring all kind of devices of our customers. In order to get a correct overview of sensors in down-mode, I'd like to build a custom map ( assuming custom alarm list is only possible this way) but with seperated group names. let me explain:

Under the rootnode we have the following architecture: <remote_probe> / <<customer name>> / <<description of the building >> / << type of installation>> <<Device>> / <<sensor>>.

So, a customer can have multiple buildings, multiple installations ( IT, OT, Telecommunication, CCTV, ....) and multiple devices.
In the custom map I would like to see the first group, the customer name, cause when a device goes down, our Service Department must see immediately which customer is involved, without clicking. When I use "Group" in the HTML-code of a map, I only see the last group (device) .

How can this be achieved ?

Best regards,

Piet

alarm custom-map group