  The accurate localization of gravitational-wave (GW) events in low-latency is
a crucial element in the search for further multimessenger signals from these
cataclysmic events. The localization of these events in low-latency uses
signal-to-noise ratio (SNR) time-series from matched-filtered searches which
identify candidate events. Here we report on an improvement to the GstLAL-based
inspiral pipeline, the low-latency pipeline that identified GW170817 and
GW190425, which automates the use of SNRs from all detectors in the network in
rapid localization of GW events. This improvement was incorporated into the
detection pipeline prior to the recent third observing run of the Advanced LIGO
and Advanced Virgo detector network. Previously for this pipeline, manual
intervention was required to use SNRs from all detectors if a candidate GW
event was below an SNR threshold for any detector in the network. The use of
SNRs from subthreshold events can meaningfully decrease the area of the 90%
confidence region estimated by rapid localization. To demonstrate this, we
present a study of the simulated detections of $\mathcal{O}(2\times10^4)$
binary neutron stars using a network mirroring the second observational run of
the Advanced LIGO and Virgo detectors. When incorporating subthreshold SNRs in
rapid localization, we find that the fraction of events that can be localized
down to $100~\mathrm{deg}^2$ or smaller increases by a factor 1.18.
