Problem with display of Relationship Name

I have a table called ys_session_detail which is the DESTINATION of a relationship.
As you can see on the attached file, the display name of the table ("Asistentes") appears correctly on the related table tab, but not on the other two slots that I have encircled on the attachment.
The relationships.ini of the SOURCE table reads:
[ys_session_detail]
ys_session_detail.ys_session_id = '$id'
action:label = Asistentes
Where else should I indicate the display label of the destination table so that it is shown instead of the raw table name?
Thanks in advance.