  Flexible-grid wavelength-division multiplexing is a powerful tool in
lightwave communications for maximizing spectral efficiency. In the emerging
field of quantum networking, the need for effective resource provisioning is
particularly acute, given the generally lower power levels, higher sensitivity
to loss, and inapplicability of digital error correction. In this Letter, we
leverage flex-grid technology to demonstrate reconfigurable distribution of
quantum entanglement in a four-user tabletop network. By adaptively
partitioning bandwidth with a single wavelength-selective switch, we
successfully equalize two-party coincidence rates that initially differ by over
two orders of magnitude. Our scalable approach introduces loss that is fixed
with the number of users, offering a practical path for the establishment and
management of quality-of-service guarantees in large quantum networks.
