PULLING SIMS will work but be warned. Verizon has the device ID tied to the line you upgrade. So last year when my wife's line was upgrade ready I used that upgrade and when the phone came, pulled the sim out of the new phone, put mine in and then put her SIM in my old phone. It Worked fine except.... this year when I went to upgrade even though 50% had been paid off on the 7plus I couldn't upgrade the line because the "device ID does not match the phone number of the device" I had to call verizon and it took them an hour to get the device ID to match correctly so then I could upgrade.
For anyone in my situation, upgrade on different line, the easiest way to get it on the right phone is as follows: activate new phone on the line it’s assigned to. After that, go to Verizon and choose “Switch devices”, and that should be it. We’ll see how it goes on Friday.