In OBEOs UML-Designer 8, how define a create-message for sequence diagram

Question

In OBEOs UML-Designer 8.0.0, plugged into eclipse Oxygen.2, I work on a sequence chart. The palette tool offers me to create actors, classes, synchronous and asynchronous messages, but neither creation nor deletion messages.

How can I specify a message opening (or closing) another lifeline with proper indenting?

If not possible directly through a wizard, I also appreciate hints how to compose this the low-level way directly in the model explorer. I know that the "asynchronous message" wizard creates a related set of

• 2 Message Occurrence Specifications (sender & receiver)
• 1 Behavior Execution Specification
• 1 Execution Occurence Specification (finish)
• 1 Opaque Behavior
• 1 Message

inside my model, which could all be created manually in the model explorer. Besides this the Message object has a property which can identify it as "Create Message", but unfortunately this is not the whole solution to the problem, as the connected fragments apparently do not match.

Searching for sequence chart semantics (e. g http://mit.bme.hu/~micskeiz/sdreport/uml-sd-semantics.pdf) gives not enough hints which objects have to be connected to the creation message and how the relationships need to be defined.