Serialization

The company I just joined went live about 10 months ago with Serialization turned off. A custom field was created for shipping to enter a serial # into at time of shipment. (only about 4 different part #'s). Service can not view this serial# info when they create cases, etc....I've been told by Netsuite that the part #s in question can not be changed to have serialization turned on. Would the following scenario work for us going forward:
1) Inactivate the 4 part #s (ABC, DEF, GHI, JKL)
2) Create new serialized part #'s (ABC, DEF, GHI, JKL) - notice same # used
Hoping that this will allow us to keep same part #s and be able to track serial #'s going forward. The only problem left would be how to somehow input all of the 10 months of serial # shipment history???