  The basic entanglement-swapping scheme can be seen as a process which allows
to redistribute the Bell states' properties between different pairs of a four
qubits system. Achieving the task requires performing a von Neumann
measurement, which projects a pair of factorized qubits randomly onto one of
the four Bell states. In this work we propose a similar scheme, by performing
the same Bell-von Neumann measurement over two local qubits, each one initially
being correlated through an X-state with a spatially distant qubit. This
process swaps the X-feature without conditions, whereas the input entanglement
is partially distributed in the four possible outcome states under certain
conditions. Specifically, we obtain two threshold values for the input
entanglement in order for the outcome states to be nonseparable. Besides, we
find that there are two possible amounts of outcome entanglement, one is
greater and the other less than the input entanglement; the probability of
obtaining the greatest outcome entanglement is smaller than the probability of
achieving the least one. In addition, we illustrate the distribution of the
entanglement for some particular and interesting initial X-states.
