I have some experience in merging companies and cultures from both rural Canada to the deep south in the USA – and absolutely a unique integration plan is necessary. Due to different jurisdictions, legal and being culturally aware – it is crucial that some elements of the plans be different to cater to the unique needs of each geographical region. I think the baseline factors you could consider reusable are the one deemed as non-negotiable by your company – ultimately the processes and procedures which make up the standards of your organization.
