The club should record the sporting reason, duration and organisational effects in a clear notice. The notice should cover training location, contact person, expected duties, medical support and the treatment of bonuses. A short, coherent process protects both sides better than contradictory individual instructions.
The player should keep the contract, amendments, line-ups, training plans, messages and pay statements in chronological order. A table with date, position, training or match, instruction, response and practical result can show whether the event was a one-off tactical decision or a permanent change to the work.
If both parties want an agreed adjustment, they should record the position, start date, duration, training duty, remuneration, bonuses, medical conditions and return to the former role in writing. A clear amendment reduces later disputes about interpretation.