The LIGO-Virgo-KAGRA (LVK) collaboration has published about 90 gravitational wave observation since the first detection in 2015, majority of which have been from binary black holes. With such a statistically significant number of events it is possible to infer astrophysical distribution of black hole masses and spins. Of particular interest are spins(mis-aligned with the orbital angular momentum) of the component black holes in a binary, as they can shed light on the binary formation mechanism. Spin-misalignments of the component black holes leave their imprints on the waveform. One such modulation is due to an asymmetry between the +m and -m multipoles of the harmonic decomposition of the gravitational wave signal from the binary. This is not included in most signal models used in LVK analysis to date. I will present the first frequency-domain model of the asymmetry in the dominant co-precessing-frame signal multipole throughout inspiral, merger and ringdown. This model has been incorporated into the latest iteration of PHENOM family of precessing-binary models (PhenomXO4a) that will be used for analysing data from the fourth observing run (O4) of the LVK. I will briefly describe the features captured in PhenomXO4a and the prospect of spin measurements using this model.