If an object acquires a pair of linked abilities as part of the same effect, the abilities will be similarly linked to one another on that object even though they weren't printed on that object. They can't be linked to any other ability, regardless of what other abilities the object may currently have or may have had in the past.
Le +4 que Nicol Bolas a acquis de Karn est lié au -14 que Nicol Bolas a acquis de Karn.
Le +4 que Nicol Bolas a acquis de Karn n'est pas lié ni au -14 de Karn.
Le +4 de Karn n'est pas lié ni au -14 que Nicol Bolas a acquis de Karn.
Aucun des +1, le +2, le -12 de Nicol Bolas n'est lié à une autre capacité.