Delete a Sub Object Type attribute in 4.6C from 4.0B

[Kevin Yu]

Hi,
 
I am working on 4.0B to 4.6C upgrade.
 
We have a subtype ZFIPP of FIPP.  A custom attribute was created in
ZFIPP at 4.0B.  After the system is in 4.6C, we found that ZFIPP cannot
be generated due to the attribute is referencing a SYST field and this
SYST field has been dropped in 4.6C.
 
First, it seems that we cannot change Data type reference (cannot change
the reference field) in 4.6C.  Second, we cannot delete the attribute
and redo it.  While we were deleting the attribute, 4.6C system
complains about the attribute is from other system and cannot be
deleted.
 
Is there any way to fix this problem?
 
 
Thanks,
 
Kevin.