I have the same problem with Oracle 9i.
I'm using jboss304
It seems that nobody knows the solution.
I found that since 3.2.2RC3 insert-after-ejb-post-create container configuration option is introduced.
It helps me!
<container-configuration extends="Standard CMP 2.x EntityBean">
<container-name>Insert after ejbPostCreate</container-name>
I forgot to say that earlier I have to make cmr field nullable, because it impossible to set relations in ejbCreate method.
But now I can make it NOT NULL, because I can configure container to execute INSERT statement after ejbPostCreate where I can setup relations.
Now cmr-field of the child bean can not be setten to null when I trying to remove parent bean and transaction fails. It is what I need.