Henneberg1[mats_, a_, b_] :=
 Flatten[Table[
   Table[MatrixForm[
     Join[
      Join[mat, ConstantArray[0, {Dimensions[mat][[1]], 2}], 2], {
       Flatten[Append[
         Append[
          Append[ConstantArray[0, (i - 1)*2], {a, 1}],
          ConstantArray[0, Dimensions[mat][[2]] - 2*i]],
         {-a, -1}]],
       Flatten[Append[
         Append[
          Append[ConstantArray[0, (j - 1)*2], {b, 1}],
          ConstantArray[0, Dimensions[mat][[2]] - 2*j]],
         {-b, -1}]]
       }
      , 1]],
    {i, Dimensions[mat][[2]]/2}, {j, i + 1, Dimensions[mat][[2]]/2}],
   {mat, mats}]]