You could handle this by concatenating all your messages together and displaying them together:
It seems that the Show Validation Message activity does not allow you to display returns, so you should use something meaningful as a separator, e.g. ';'.
Thanks a lot! The problem is solved.
Kind regards,
Bas
You can also try something like this: (http://i.imgur.com/hNhcVxU.png?1)
This flow kicks in the moment you press the 'Save' button. If there are errors, all the validation feedback will be shown. If there are no errors, the entity will be saved.