LaTeX: Rotated header lines in table beginning in the same line

LaTeX: Rotated header lines in table beginning in the same line

i have a table with rotated text. All these header lines should start near the second hline (similar to "Abs.") like
hline
   C
  BC
  BCD
1 BCD
l BCD
o BCD Frequency
CABCD Abs   Rel
hline


\begin{table}[htbp]
\begin{tabular}{rrrrrrr}
\hline
\multirow{6}{*}{\rotatebox[origin=cb]{90}{Col1}} & \multirow{6}{*}{\rotatebox[origin=cb]{90}{A}} & \multirow{6}{*}{\rotatebox[origin=cb]{90}{BBBBB}} & \multirow{6}{*}{\rotatebox[origin=cb]{90}{CCCCCC}} & \multirow{6}{*}{\rotatebox[origin=lc]{90}{DDDDD}} & & \\
& & & & & &\\
& & & & & &\\
& & & & & &\\
& & & & & \multicolumn{2}{c}{Frequency} \\
& & & & & Abs. & Rel.\\
\hline
1&9&8&7&6&5&4\\
\end{tabular}
\end{table}
i tried different origin like l, r, cB, cb, ct, ... but it doesn't look like the way i would prefer. what do i wrong? thank you!