The school can pool the generic Ever6 PP funding, but the PP for LAC and former LAC (until recently known as the Pupil Premium Plus) should be spent on things above and beyond the school's universal offer which will raise the academic attainment of that particular child.
Other children may benefit from the PP spend; for example, social skills groups or counselling services which the school buys in; but the PP that LAC and former LAC attract should not be used to fund interventions the school are already running, such as literacy withdrawal groups or SATs booster classes. The generic/Ever6 PP however, can be- and, as vulnerable children, LAC and former LAC should benefit from this too.
Ofsted (and for LAC, the Virtual Head) will want to see evidence of how the PP money for LAC and former LAC is being spent to raise the attainment of the child who attracts it, as Devora and Velvet say.
Broadly speaking, the PP for LAC and former LAC should not be used to plug any gaps in services; nor is it only used to help children who are academically behind. It should be used to help each child achieve their potential- whether this is through raising aspirations through extra university/museum visits, or tutoring at home, or technological equipment.
The EEF/Sutton Trust toolkit can be a good starting point for discussion with schools who are struggling to spend the money effectively.