The preservePatches constraint in decomposeParDict can be used to keep owner and neighbour cells of coupled patches on the same processor. It previously only handled one-to-one coupling (cyclic, processor) but has been extended to handle many-to-one coupling (cyclicAMI, cyclicACMI).
Without syncing across (in green) cyclicAMI:
With syncing across (in green) cyclicAMI:
