Promptly, once a material change is known or proposed, so the transfer can be assessed on accurate facts before the applicant relies on the old plan.
Keep a dated change record
Record what changed, when it takes effect and which duties or entities are affected. A professional can then assess the relevant procedural consequences. Do not substitute a revised internal start date for that review.
Identify what is confirmed, what remains uncertain and whether duties or support will change. Disclosure alone tells a reviewer that something changed; it does not by itself confirm that the organizations still meet the ongoing requirement of actually operating as an employer in multiple countries, a standard that continues throughout the stay rather than being satisfied once at the start. A restructuring that changes ownership, reporting lines, or which entity actually employs people can affect whether that continuing requirement is still met, even when the underlying business relationship between the two sides looks unchanged from the outside. Confirm which entity now functions as the employer on each side of the arrangement, and whether that entity still operates as a real business rather than existing mainly on paper, before treating the disclosure itself as sufficient. Keep the analysis of that operating requirement separate from the procedural question of when and how the change was reported, since a prompt disclosure does not answer whether the organizations still qualify under the standard that applies for the whole duration of the stay.