Combining custom bar line with standard elements

[Fr. Samuel Springuel]

I have a couple of customized bar lines defined and have come across an 
instance where I want to combine them with a standard bar line element.  
However, my naive attempts aren’t working as expected.  My first attempt 
resulted in the bar line simple disappearing; in the second the customization 
disappeared.  How can I make the combination while still preserving my 
customization?

\version "2.20.0"
\language "english"

\layout {
    \context {
        \Staff
        \override BarLine.before-line-breaking =
        #(lambda (grob)
             (let ((glyph-name (ly:grob-property grob 'glyph-name)))
                 (if (member glyph-name '("[" "]"))
                     (begin
                      (ly:grob-set-property! grob 'thick-thickness 2)
                      (ly:grob-set-property! grob 'font-size -4)
                      )
                     )
                 )
             )
    }
}

\defineBarLine "[" #'("" "[" "")
\defineBarLine "]" #'("]" "" "")
\defineBarLine "]." #'("]." "" "")

global = { \key f \major }

music = {
    g' f' e' d' \bar "["
    f' g' a' g' \bar "|"
    f' e' c' d' \bar "]."
}

\new Staff
<<
    \new Voice = "mel" { \global \music }
>>


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Fr. Samuel, OSB
(R. Padraic Springuel)
St. Anselm’s Abbey
4501 South Dakota Ave, NE
Washington, DC, 20017
202-269-2300
(c) 202-853-7036

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