As of today, it is not possible to do what you are asking, though you are not the first to request this capability be added.
As of today, in a nutshell:
- If the data is created by the user, it can be synched across devices.
- If the data is created by the FAA, then it must be downloaded separately on each device directly from the Internet.
And for what it's worth, even when you synch user-created data across devices, you're still uploading it from the Source device to the iFly cloud across the Internet, and then downloading it to the Recipient device from the iFly cloud across the Internet--you're not transferring those data directly from device to device.
(There is a separate feature where you can share Flight Plans directly between devices that are all connected to the same local wi-fi network, but that is a different feature than the synch feature.)