  We have implemented ad-hoc modifications to the CORSIKA Monte-Carlo generator
which allow us to simultaneously adjust the multiplicity, elasticity and
cross-section of hadronic interactions with respect to the predictions of the
Sibyll 2.3d interaction model, in order to assess whether a reasonable
combination of changes (that is not excluded by current experimental data)
could alleviate the observed tension between the model predictions and observed
features of extensive air showers induced by ultra-high energy cosmic rays
(UHECR). Previously, we have studied the effects of such changes on
proton-initiated showers. Because a multitude of experimental data suggest that
the primary composition of the UHECR is mixed, we have expanded the
modification procedure to include nuclear projectiles in a consistent way based
on the superposition model, in a similar manner as was used in the previous
studies carried out using one-dimensional simulation methods. As we are using a
fully three-dimensional approach, we can quantify the effects of the changes on
both longitudinal and lateral features of the showers. With the inclusion of
nuclear projectiles, we can study the impact of the changes on observable
quantities for realistic primary beams as well as on the determination of the
primary composition from data under the assumption of the modified hadronic
interactions.
