Hello,
I have an offer on my family plan where I can add a new line and get $830 off on an iPhone 15 pro max with 36 months of credits. I currently have 5 lines on my family account, mostly all with the same plans. I plan to use the new line added for my son but since it's an expensive phone I don't want him to use it as he might lose it ( he is in 7 grade).
My question is after activating the new line with the device credits, am I able to swap the SIM between my other device which has the same plan but no device payments or anything without losing the monthly 36 credits on the original new line added?