  We set out to explore how best to mitigate the number of period aliases for a
transiting TESS system with two identified transits separated by a large time
period on the order of years. We simulate a realistic population of doubly
transiting planets based on the observing strategy of the TESS primary and
extended missions. We next simulate additional observations using photometry
(NGTS) and spectroscopy (HARPS and CORALIE) and assess its impact on the period
aliases of systems with two TESS transits. We find that TESS will detect around
400 exoplanets that exhibit one transit in each of the primary and extended
missions. Based on the temporal coverage, each of these systems will have an
average of 38 period aliases. We find that, assuming a combination of NGTS and
CORALIE over observing campaigns spanning 50 days, we can find the true alias,
and thus solve the period, for up to 207 of these systems with even more being
solved if the observing campaigns are extended or we upgrade to HARPS over
CORALIE.
