I have written here about the basic settings of most German folksy wind music a few times before.
The melody comes in a mostly three part setting with the 1st and 2nd flugelhorn plus the 1st Bb Tenorhorn being the intended carriers of these lines.
The bass line comes in Tuba 1 (high octave) and Tuba 2 (low octave). Tuba 2 should definitely be given preference if only one tuba.
Harmony/off-beats is/are written in 4 horn parts ( 2nd & 4th also written into the 2nd & 3rd Bb Tenorhorn parts). 1st & 2nd trombone play similar patterns. The 3rd trombone mostly plays a high bass line. The basic 6-tet expects the harmony line being represented by horn 1 or trombone 1.
Bb Bariton (the fat one compared to the Tenorhorn) has a part which is a mix of the melody taken an octave down and a high bass line (sometimes embellished as an Alberti bass line). In marches the Tenorhorn 1 and the Bariton often split in thirds after the first 8 bars of the tenor melody.
In bass solos the above pattern is broken, as all Tenorhörner, the Bariton, and all trombones join in with the tuba.
Drums are considered the 6th member of the basic sextet. Which also has a dance band type variant:
Trumpet 1 (with flugelhorn 1 cues), Eb alto sax, and Bb tenor sax play the same 3 part setting of the melody. Guitar or accordion fill the harmony lines, and bass guitar does the bass line. Drums are the same. As long as the basic 6 functions are filled you may mix and match the traditional and dance band set-ups.
From the basic 6-tet it is possible to get parts up to a full wind band or a folksy big-band. The latter genre sometimes is seen as the stage band in the huge TV co-productions of the German speaking countries. The trumpet section mostly plays flugelhorns, the trombone section will double on ovals, the bass doubles on tuba, the woodwinds play a lot of high clarinet stuff. Accordion replaces piano.
Point is that even if the clarinets may add some really fun stuff (aside of frequent doubling the 3 part melody setting in the upper octave), they are not bearers of the essential lines.
The master concept behind the post-WWII folksy wind revival was shaped by the late Ernst Mosch, who was born in the Egerland part of the politically much disputed Sudetenland. The Germans were rough on the Czechs during the war. The Czechs threw out the Germans after the war (which is the reason for the many brass makers in Bavaria). Mosch first became trombonist in a radio big band. There he certainly learned about the thickened line and took it to the traditional music. Mosch started a large edition company selling music for the settings outlined above here. His own large touring band didn’t exactly play the instruments mentioned on the parts. His signature sound was very fat, as he used flugelhorns on the 2nd & 3rd trumpet parts (usually there were 5 flugelhorns, 1st doubled). The lone 1st trumpet then was very much featured on counter fanfares. Usually no horns and no bass trombone, 6 in the Tenorn/Bariton section. 1 F & 1 BBb tuba. 1 Eb & 2 Bb clarinets. Snare, cymbals, and bass drum spread on 3 players.
For certain repertory variants the line-up would vary. An Alp related CD & tour added 2 horns alluding to alp horns. Another project added a saxophone section.
I recently wrote on the Oberkrainer concept out of Slovenia with its use of the bell front baritone:
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Interestingly this style also is influenced by jazz especially in its chord structure, whereas Mosch is traditional in his tonal concept sometimes incorporating old folf modes like the lowered leading note. As said Mosch took the thickened line concept from big band jazz.
Klaus