I've found that some recent iMessage messages that were sent to me showed up only on my iPad instead of both my iPad and my iPhone. There are other questions at Ask Different that address how this could happen, but my concern here is getting the message streams back in sync so that both devices show the same history of messages. In other words, I want to get the missing messages to appear in the message stream on my iPhone (with the correct timestamps). Is there some way to force the iPhone to sync with the iPad or with a master message database at Apple?
Both devices are running iOS 9.3.5.
Best Answer
There is no master message database at Apple. If it's been less than 30 days, and if Apple's servers think your iPhone hasn't received the messages in question yet, they may yet show up, but it's unlikely.
There's no way to force the issue because messages are only saved for up to 30 days or until delivered, whichever comes first. If their servers think the messages have been delivered, they're already gone.