  A critical requirement of spectroscopic large scale structure analyses is
correcting for selection of which galaxies to observe from an isotropic target
list. This selection is often limited by the hardware used to perform the
survey which will impose angular constraints of simultaneously observable
targets, requiring multiple passes to observe all of them. In SDSS this
manifested solely as the collision of physical fibers and plugs placed in
plates. In DESI, there is the additional constraint of the robotic positioner
which controls each fiber being limited to a finite patrol radius. A number of
approximate methods have previously been proposed to correct the galaxy
clustering statistics for these effects, but these generally fail on small
scales. To accurately correct the clustering we need to upweight pairs of
galaxies based on the inverse probability that those pairs would be observed
(Bianchi \& Percival 2017). This paper details an implementation of that method
to correct the Dark Energy Spectroscopic Instrument (DESI) survey for
incompleteness. To calculate the required probabilities, we need a set of
alternate realizations of DESI where we vary the relative priority of otherwise
identical targets. These realizations take the form of alternate Merged Target
Ledgers (AMTL), the files that link DESI observations and targets. We present
the method used to generate these alternate realizations and how they are
tracked forward in time using the real observational record and hardware
status, propagating the survey as though the alternate orderings had been
adopted. We detail the first applications of this method to the DESI
One-Percent Survey (SV3) and the DESI year 1 data. We include evaluations of
the pipeline outputs, estimation of survey completeness from this and other
methods, and validation of the method using mock galaxy catalogs.
