Mass-mass diagrams for the PSR J2222–0137 system at the zone of high non-linearity where a fast transition to a strongly scalarised NS happens. PK parameters are obtained by fitting the DD model to the timing data from Guo et al. (2021b). Calculations are preformed within DEF gravity for the MPA1 EOS allowing NSs with maximum mass in GR of M_GR ≃ 2.46 M_⊙. Left panel corresponds to the point in the DEF gravity parameter space with α₀ = −10⁻⁴, β₀ = −4.3, which is not excluded by the test. Right panel shows the same test but for α₀ = −10⁻⁴, β₀ = −4.35. The prediction of a strong dipolar contribution ${\dot{P}}_{\text{b}}^D$ fails the test for the more negative β₀ = −4.35. The axes correspond to the masses of the pulsar m_p and the companion c. The shadowed area is the allowed region at 68% confidence level (CL) limit for a corresponding PK parameter. The solid green line corresponds to the observed value of ${\dot{P}}_{\text{b}}^{GW}$ due to the GW emission.