Upgrade swap question

[eenieMINI]

I have a scenario to run by any of the Sprint guys or users who may have experienced the same.

I have a family share plan everything plan... both lines are eligible for upgrade. My other son has his own account which is not yet eligible for upgrade. Could I order an upgrade on one of my lines (thus extending contract and all that) and when it arrives not activate the phone, give it to my son who will activate it on his own line or is the esn on the new phone tied to my account?
This is legit... not a money making scheme just trying to get my son a phone since his is trashed. I have no problems with renewing my contract because I'd do that anyway when I upgrade my part of the plan.