[rules-users] Inserting (asserting) objects during LHS evaluation - side effects?

All- What are the potential side effects of asserting objects during LHS evaluation, specifically a FROM clause? For example, using the example from the docs, let's assume that the zipcode property is in fact a field that's calculated via business rules. So, I'd like to perform just-in-time insertion of the person's address and perhaps other objects as well necessary to the calculation. In other words, I'd like to implicitly assert objects on-demand as they're needed. For the curious, this is something that's possible in Blaze Advisor using their is-needed rules, and for which I'm attempting to find a corresponding capability in Drools. I guess it comes down to the question of whether insertObject() is reentrant. Anybody have a clue? Or another way of approaching this? For reference, here's the documentation example using the from clause: rule "validate zipcode" when Person( $personAddress : address ) Address( zipcode == "23920W") from $personAddress then # zip code is ok end