Hi Amy
There is no field PERSON.CREWID. So, I'm not sure how to answer this. There is however a WORKORDER.CREWID, but you shouldn't be seeing that as it should have been superseded with WORKORDER.AMCREW.
The WORKORDER.CREWID field has a sigoption applied to the field (CREWIDFIELD) which you can see in Signature Security as "Crew field", however, there is also a restriction to not display the field com.ibm.tivoli.maximo.amcrew.CrewIDHider.
Normally to create a crew, you need to go and create a Crew Type, then using the Crews application, assign a labor to the crew in the correct position. Additionally, you will need to mark the craft as Crew enabled.