I don't think this is possible anymore. It was possible in version 1.1, but since the configurable data tree in version 2.0 it is not possible anymore.
But maybe I'm wrong. Does anybody else know ?
It is technically possible. However it is not recommended. This traces to the way the Toolbox is organizing data in the data-matrix. It is by two distinct features - "Endpoint" as you call it(I’m assuming here), and a dynamic configurable part based on metadata. They are also known as predefined and dynamic tree.
The first is a predefined hierarchy of strings (e.g. "Human healthhazards#Genetic Toxicity", this encodes a two level hierarchy) and the second comes from the data needed to be displayed. Think of the former as the highest order id key while the latter as a configurable visualization option.
This brings some intricacy to the way a "new endpoint" cohabits with the metadata being displayed on the datamatrix.
If for instance we have some data imported to EcotoxicologicalInformation#Aquatic Toxicity node and we need to display it. With no dynamictree we would just see all datapoints under the EcotoxicologicalInformation#Aquatic Toxicity node. if we however et that we want the"Duration" metadata field to be displayed bellow the aforementionednode you will have the first two levels and sublevels that look something like"96 h", "48 h" etc.
Now if you import data to Ecotoxicological Information#AquaticToxicity#SomeAquToxSubTax and display both your and the existing data you willhave a tree that has two levels ("Ecotoxicological Information" and"Aquatic Toxicity" bellow it) and the next level will be a mixture of the "SomeAquToxSubTax " and "96 h", "48 h", etc.The data is all there but it is visually unappealing.
However, you can experiment with it and see if it works for you.
To "create a new endpoint" using horizontal layout you need to add the new node in your "Endpoint tree path" column (e.g. "Ecotoxicological Information#AquaticToxicity#SomeAquToxSubTax" or simply "MyNewTopLevelTax").
Using vertical layout you can create the new node using a popup menu in the"Data tree position" tree view control.