Ice microphysical processes modulate cloud structure, evolution, and Earth's radiative balance, yet secondary ice production (SIP)—whereby fragmentation enhances ice number concentrations (<em>N</em><sub>ice</sub>) beyond what ice-nucleating particle (INP) populations alone can explain—remains poorly constrained. We develop a drop-shattering parameterization based on laboratory-observed pressure release event frequencies during drop freezing and evaluate it, alongside a water-activity-based immersion-freezing model for primary ice formation, in large eddy simulations (LES) of a tropical cumulus congestus case from NASA CAMP<sup>2</sup>Ex—the second of a two-part study extending liquid-phase results from Part I into the mixed-phase region. Bin and double-moment bulk simulations are evaluated against in situ aircraft observations from 0 to -15 °C. The baseline parameterization negligibly enhances <em>N</em><sub>ice</sub>; a 10× multiplier on per-event splinter numbers—reflecting substantial production uncertainty—increases <em>N</em><sub>ice</sub> by 1–2 orders of magnitude. The bulk scheme reaches localized maxima near 10<sup>3</sup> L<sup>-1</sup>, while the bin scheme reaches 10–20 L<sup>-1</sup>, reflecting fundamentally different collision-kernel structures between the schemes. A primary-secondary ice feedback emerges exclusively in the bin scheme, driven by INP enrichment of precipitation-sized drops through collision-coalescence and INP accumulation; this feedback is absent in the bulk scheme due to its lack of aerosol core mass tracking. The 10× parameterization partially reconciles a 1–2 order-of-magnitude deficit in simulated concentrations for sizes > 200 <em>μ</em>m relative to observed particle size distributions, with turbulence-induced collision enhancement essential for conditioning SIP efficiency. Together, these bin and bulk implementations provide a foundation for improving SIP representation in large-scale models.