input stiffness matrix to ansys

Hi everybody

Im working on a project about Finite element modeling of Contact. Im not allowed to use contact solving feature of ANSYS and i should use its Macro Programming. in this case i should read stiffness matrix from ansys, add some row and column to it and input it back to ansys and solve it.

I have two problem with this, first i dont know how to input modiffied stiffness matrix back to ANSYS..

secound one, how to add new unknowns to displacement vector in: [k][u]=[f] relation ,wich this new unknown, called Lagrangian multipliers, are correspond to new raw and columns of stiffness matrix.

thanks by the way..