Use message / data in different area's HMTL email template ?

I'm using for the welcome and password email SB welcom email plugin. This works fine with HTML email templates plugin.

Now I have set a custom test HTML template but when I put message it pick up the body from the SB welcome plugin, that fine. But I would like more in control and put for example the login details somewhere else in the html template.

Could you please let me know how I can fix this.