How do you have a different iMessage account on the 2nd device but logged into the same Apple ID on both devices?
I would speculate that messages sent to a particular phone number would be handled differently.
Suppose I have two phones. Each has a different phone number. And each should receive text messages sent to those phone numbers, regardless of whether they share the same iCloud account.
I would hope that iMessage had been smart enough in its original implementation to know which phone to send text / iMessage messages to based on which phone number was texted (even if both phones were logged into the same iCloud account).
I speculate that this scenario is what the original poster is describing.
He now wants to know what happens if he turns on iMessages in the cloud. Will both phones now be synced because they are logged into the same iCloud account? Or will they keep their independence based on the fact that they are separate entities?
My belief, is that they should not be synced, because different phone numbers have a different purpose. I would not want my personal text messages blended with my business messages (for example) if I had two phones specifically to separate business from personal.
Perhaps in a corporate sense, you wouldn’t log your company supplied phone into your personal account. But what about the self-employed??
I have owned businesses. And I kept two phone numbers and two emails. One for the business that I stopped answering at 6:00 pm. And a personal number and email that I used all day and night.
That way personal friends can call or message me, and after 6:00 pm I wasn’t trying to guess if it was a personal or business call. If they were calling on my personal phone, then obviously it was someone I had given permission to do so.
But, what if the new iMessage in the cloud blends them as the original poster asks???
Then I now have messages from clients on my personal phone and personal messages on my business phone. Which can get messy. And such a scenario could cause me to accidentally reveal my personal phone number or email if I replied (sometimes it could happen without my reply as iMessage does fill in blanks sometimes when I’ve messaged someone and didn’t have all their information).
So I see his question as quite valid.
Based on his question, I would ask one step further... what about when you have a family iCloud account? I certainly wouldn’t want my daughter’s messages getting synced and blended with mine. They certainly have no reason to know everything I send.
And if it’s not a family account, I could likewise see spouses using the same iCloud account without family sharing. Then we update the same calendar, and never have the whole what are you doing on this day mixup. It’s a royal pain to sit and exchange our constantly changing weekly schedules. So sharing the same iCloud account would help there.
Likewise, our contacts and address books would be merged. Which in a long term relationship or marriage is generally more convenient from my experience.
But, even as a couple, if we shared the same iCloud account, neither of us would want our text or iMessages getting blended and sent to both spouses phones.
While we would certainly trust each other, I do believe in trust being based on your faith in me. Not based on you read everything I send or receive. I have never sat and went through a spouses phone. I believe that the second I think it might be necessary to go through their phone, that enough is already wrong that I should just end the relationship. Trust is the most important part of a relationship. As soon as that is gone, then there’s no reason to continue. So if I feel that I must look at someone else’s messages, then obviously the trust isn’t there. And whether justified by something I’ve learned, or just unjustified paranoia, it’s time to end the relationship. That goes both ways obviously.
So, with the above scenarios, I agree with the original poster, that this needs fully explained.
Apple should release a detailed description of what the new feature does in depth. A surface explanation of, it syncs across your devices, is woefully inadequate.