Sync stock between regions

Hi friends! Please advise on any possible way to sync stock quantities among various regions (UK/US/AU/JAPAN) for FBM listings with the same SKU. As far as I understand, the quantities are auto-synced within the same region; for example, in the EU, it syncs UK and Germany stock. But how can I sync between the UK and the US? I do not use the Build International Listing tool, as it is useless and only syncs the price.