  A free multiarrangement of rank $k$ is defined to be extendable if it is
obtained from a simple rank $(k+1)$ free arrangement by the natural restriction
to a hyperplane (in the sense of Ziegler). Not all free multiarrangements are
extendable. We will discuss extendability of free multiarrangements for a
special class. We also give two applications. The first is to produce totally
non-free arrangements. The second is to give interpolating free arrangements
between extended Shi and Catalan arrangements.
