Construct a harmonious chain of chord progressions that enhance the presented musical piece.
"^Vorspiel" | g | .f.f .e.e | .d.d B>g | ff dc'/f/ | gb/a/ g || [ge] |: 
 .[fd][fd] .[ec][ec] | .[dB][dB] [BG]>[gB] | [fd][fd] [dA][c'd]/[fc]/ | 
 [gB][gB]/[ac]/ [bd]>[gB] | .[fd][fd] .[ec][ec] | .[dB][dB] [BG]>[gB] | 
 [fd][fd] [dA][c'd]/[fc]/ |1 [gB][bd]/[ac]/ [gB][gB] :|2 [gB][bd]/[ac]/ !fermata![gB]2 || 
[K:D] |: [fd]/[af]/[af] [bg]>[af] | [ge][AE] [cA]/[BG]/[cA] | 
 [ec]/[AE]/[cA]/[ec]/ [af]>[ge] | [fd][AF] [dA]/[cG]/[dF] | [fd]/[af]/[af] [bg]>[af] | 
 [ge][AE] [cA]/[BG]/[cA] | [ec]/[AE]/[cA]/[ec]/ [ac]>[cA] | [dF][dF][dF]"^d.C." z :| 
[K:C] |: [eG]>[dF] [cE][cE] | [cE]/[BD]/[cE]/[dF]/ [eG]2 | [dF]>[gB] [^f^A][gB] | 
 [ac]/[gA]/[eG]/[cE]/ [GC]2 | [eG]>[dF] [cE][cE] | [cE]/[BD]/[cE]/[dF]/ [eG]2 | 
 [dB][gB]/[eG]/ [fG]>[BF] |1 [cE][cE][cE] z :|2 [cE][cE][cE] |]  
X:1
L:1/8
M:2/4
K:G
"^Vorspiel" | g |"D7" .f.f .e.e |"G" .d.d B>g |"D7" ff dc'/f/ |"G" gb/a/ g || [ge]"B" |: 
"D7" .[fd][fd] .[ec][ec] |"G" .[dB][dB] [BG]>[gB] |"D7" [fd][fd] [dA][c'd]/[fc]/ | 
"G" [gB][gB]/[ac]/ [bd]>[gB] |"D7" .[fd][fd] .[ec][ec] |"G" .[dB][dB] [BG]>[gB] | 
"D7" [fd][fd] [dA][c'd]/[fc]/ |1"G" [gB][bd]/[ac]/ [gB][gB] :|2"G" [gB][bd]/[ac]/ !fermata![gB]2 || 
[K:D]"C" |:"D" [fd]/[af]/[af] [bg]>[af] |"A7" [ge][AE] [cA]/[BG]/[cA] | 
 [ec]/[AE]/[cA]/[ec]/ [af]>[ge] |"D" [fd][AF] [dA]/[cG]/[dF] |"D" [fd]/[af]/[af] [bg]>[af] | 
"A7" [ge][AE] [cA]/[BG]/[cA] | [ec]/[AE]/[cA]/[ec]/ [ac]>[cA] |"D" [dF][dF][dF]"^d.C." z :| 
[K:C]"D" |:"C" [eG]>[dF] [cE][cE] | [cE]/[BD]/[cE]/[dF]/ [eG]2 |"G7" [dF]>[gB] [^f^A][gB] | 
"C" [ac]/[gA]/[eG]/[cE]/ [GC]2 |"C" [eG]>[dF] [cE][cE] | [cE]/[BD]/[cE]/[dF]/ [eG]2 | 
"G7" [dB][gB]/[eG]/ [fG]>[BF] |1"C" [cE][cE][cE] z :|2"C" [cE][cE][cE] |]  