The invention is directed to systems and methods for the synchronization of two clients both utilizing a common storage platform (e.g., the new storage platform of the related inventions) to synchronize through an intermediary that is not using the same common storage platform (e.g., instead using a legacy storage platform that does not itself support synchronization for the new storage platform). Data is synchronized using the existing capabilities of the intermediary but where the data structure of the clients is preserved. An "adapter" is used to enable a client to interact with an intermediary by compensating for the intermediaries inability to preserve the data structure elements inherent to the client's storage platform. Specific embodiments are directed to either or both upload-syncing data from a client to a intermediary and/or download-syncing data from an intermediary to a client. Certain additional embodiments are further directed to compaction of data on the intermediary.