The 20-year-old has enjoyed an incredible first season in the Premier League.
The former Derby County man rescued a point for his side in Saturday's 1-1 draw at the Philadelphia Union with a superb late equaliser.
The 29-year-old vacated club captaincy this week following a number of incidents.
The pair will join the Scottish Championship side at the end of the season.
The Ivory Coast international was wonderful in the defeat by the Addicks.
The Spaniard is expected to leave if the Magpies are relegated, but they are keen to stop that happening.
The big Belgian admits that he loves when they sing his name.
West Ham United have secured their greatest ever Premier League points tally.
Ronny Deila's men are on the verge of clinching their five league crown in a row.
The 19-year-old Irish centre-back made his first Premier League start in Saturday's 3-2 loss at Watford.