Hi,
Any linking will only work from that point on.
iMessages are sent once then deleted.
They are flagged at the server for the number of devices current linked to be sent to.
Even if one device has yet to accept the iMessage it cannot be accessed by other devices.
If a device has "lost" connection it will depend how long that break is as to whether an "missing" iMessages are recoverable as it were.
SMS coverage will somewhat depend on the carrier used but it is unlikely that the iPhone will store them in a way that allows this to happen. The iPhone "Shares" the SMS/Carrier connection in a similar manner to a computer doing Internet Sharing. The SMS comes in on the phone connection and goes out to the Mac on the WiFi connection which allows the Mac to see and respond to the SMS messages.
9:06 pm Tuesday; January 24, 2017
iMac 2.5Ghz i5 2011 (Sierra)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
Mac OS X (10.6.8),
iPhone 6 iOS 10.x and an iPad (2)