Trying to add a resource results in:
TSS0351E SPECIFY "UNDERCUT" TO TRANSFER OWNERSHIP.
The ADD command for a resource is to define ownership.
For example, the following command adds the data set XYZ to department IZZE:
TSS ADD(IZZE) DSN(XYZ)
The TSS0351E message means that the RESOURCE is already owned.
If the intention is to move ownership to another department then you would have to add the UNDERCUT keyword to the command:
TSS ADD(IZZE) DSN(XYZ) UNDERCUT