step acquisiton- no control to control

sir i am kind of addled at the prospect of seeing a “gain on derecognition on disposal of an equity instrument” in the consolidated SPL, where the parent entity through a step-acquisition increases its stake from 10% to 60% during the accounting period.
(this gain relates to FV remeasurement on shares held under FVPL model. )

I mean why do we separately/additionally recognise it when preparing consolidated SPL? Would not it have been included in the individual financial statement of the parent entity already??