When inserting Dynamic Content with the Assist Edit I would expect to be able to traverse N:1 relationships with other entities.  When selecting which field to use lookups are shown differently with what appears to be the the relationship itself (rather than the display value for the look-up) shown with the entity name (see attached).  However when the relationship is selected one cannot continue to select the appropriate field in the related entity (also attached).

The documentation here:

https://docs.microsoft.com/en-gb/dynamics365/customer-engagement/marketing/prepare-marketing-emails#use-assist-edit-to-place-standard-dynamic-content

suggests this should at least be possible by manually editing the Handlebar statements but this does not appear to work either (although the syntax used in the examples in the documentation appears to be entirely wrong so we are having to guess what to put here)