Hi Christopher,
This is what I found on this topic.
Prevailing wage codes are attached at the project level. There is one effective date per code rather than laborclasss , hiearchy is Pwag, labc. So you can't add in 2 admin labc under one pwag code.
If you need different effective dates for the classes, you would need to have different prevailing wage groups. Otherwise, you could override the date and then delete the existing labc within the group and create new one under the same ID. But there is no way to find out now what the rate was in previous years.
In the code file, the field pwag is 4 char linked to pm_id15. In looking to create an ID with significant identifying information if/when using multiple prevailing wage groups , it doesn't appear that the 4 char field size can be expanded.