  Information about the behavior of zeros of classical families of multiple or
Hermite-Pad\'e orthogonal polynomials as functions of the intrinsic parameters
of the family is scarce. We establish the interlacing properties of the zeros
of Angelesco-Jacobi polynomials when one of the three main parameters is
increased by 1, extending the work of dos Santos (2017). We also show their
monotonicity with respect to (large values) of the parameter representing in
the electrostatic model of the zeros the size of the positive charge fixed at
the origin, as well as monotonicity with respect to the endpoint of the
interval of orthogonality. These results are extended to zeros of multiple
Jacobi-Laguerre and Laguerre-Hermite polynomials using asymptotic relations
between these families.
