  A version of the iterated B\"acklund-Darboux transformation, where Darboux
matrix takes a form of the transfer matrix function from the system theory, is
constructed for the discrete canonical system and Non-Abelian Toda lattice.
Results on the transformations of the Weyl functions, insertion of the
eigenvalues, and construction of the bound states are obtained. A wide class of
the explicit solutions is given. An application to the semi-infinite block
Jacobi matrices is treated.
