N-acetyl-alpha-D-galactosaminyl-(1->4)-N-acetyl-alpha-D-galactosaminyl-(1->3)-N,N'-diacetyl-alpha-D-bacillosaminyl-tri-trans,heptacis-undecaprenyl diphosphate + 3 UDP-N-acetyl-alpha-D-galactosamine = [alpha-D-GalNAc-(1->4)]4-alpha-D-GalNAc-(1->3)-alpha-D-diNAcBac-tri-trans,hepta-cis-undecaprenyl diphosphate + 3 UDP + 3 H(+) — reaction