  We present exact multi-parameter families of soliton solutions for two- and
three-component Manakov equations in the \emph{defocusing} regime. Existence
diagrams for such solutions in the space of parameters are presented.
Fundamental soliton solutions exist only in finite areas on the plane of
parameters. Within these areas, the solutions demonstrate rich spatio-temporal
dynamics. The complexity increases in the case of 3-component solutions. The
fundamental solutions are dark solitons with complex oscillating patterns in
the individual wave components. At the boundaries of existence, the solutions
are transformed into plain (non-oscillating) vector dark solitons. The
superposition of two dark solitons in the solution adds more frequencies in the
patterns of oscillating dynamics. These solutions admit degeneracy when the
eigenvalues of fundamental solitons in the superposition coincide.
