What is the effect of claiming *istibra'* (period of waiting after intercourse) regarding the legitimacy of the child born to a *mukataba* co-owned female?

Primary text

If the offending partner claims *istibra'* and she gives birth more than six months after the *istibra'*, the child does not join the lineage of the offending partner, and she does not become an *umm walad*; the status of her child follows her own status. If she gives birth less than six months after the *istibra'*, the child is deemed to belong to him, just as if the intercourse had occurred before *istibra'*, because it is established that she was pregnant at the time of *istibra'*, rendering the waiting period ineffective.