The $362 million collective sale of Cairnhill Mansions will proceed at that price, due to a settlement that gives the penthouse owner who objected to the sale an extra $867,004.79.

This sum is to be borne equally by the owners of the other units in the development, the High Court ordered on Thursday afternoon.

Mediation between objector Djie Tjoe Nio and the collective sale committee began on Tuesday and carried on "into the wee hours of the night", said Justice Quentin Loh in his oral grounds.

The $867,004.79 represents 0.25 per cent of the sale proceeds of the other 60 units.

Mrs Nio, who was originally supposed to pocket close to $15.2 million from the sale, will now get around $16 million for her 792 sq m unit.

The owners of the other units, each 188 sq m in size, will each get about $14,400 less than the $5.77 million apiece they were supposed to receive.

The law says the court can order an increase to the sale proceeds for an objector if it is satisfied that it would be just and equitable to do so. The total sum can be paid from the sale proceeds of the owners and cannot exceed 0.25 per cent of the sale proceeds for each unit or $2,000 per unit, whichever is higher.

Low Keng Huat had bought the property at 69 Cairnhill Road for $362 million in February.

Four months later, the civil engineering and property development company also bought the adjacent 67 Cairnhill Road for $100 million.

But the owner of the penthouse at 69 objected, saying the method of valuation was wrong and worked unfairly against her, leading the Strata Titles Board to issue a stop order and the collective sale committee to then apply to the High Court to approve the sale.

"Her case was not that she would suffer a financial loss," Justice Loh said, adding that the law "is a means to address specific inequities that can arise in a collective sale".