بسم الله الرحمن الرحيم
It is not lawful to do Aqiqah after the child’s death, the sunnah Aqiqah is specific with life. However, there is no harm as per the Shariah if someone slaughters animal after the death of the child and feeds it or gives it in charity. But it shall not take the place of sunnah Aqiqah. It is recorded in Fatawa Darul Uloom: “Masnoon Aqiqah is not performed after the death of child, i.e. it shall not be called Aqiqah. Further slaughtering the animal and giving its meat in charity or feeding it is right, but it shall not take the place of sunnah Aqiqah.” (Fatwa Darul Uloom Deoband: 15/623)
In case of slaughtering the animal one is free regarding the meat; he may use as much meat he wishes for his relatives as well as may give it in charity to the poor.
Allah knows Best!
Darul Uloom Deoband