When both parents exercise parental responsibility, as is usually the case even after separation, moving abroad with the children is a joint decision. Preparing it together helps prevent conflict or wrongful removal.
Mediation before departure allows discussion in a neutral and confidential setting: location and duration of the stay, schooling, time with each parent, holidays and journeys, travel costs, remote contact and conditions for returning.
Agreed points are recorded in a memo. Your lawyers can then incorporate them into a parenting agreement, approved by the court and made effective in the destination country.
I support you as mediator in preparing your project; each of you may receive advice from your own lawyer.