EOModeler Delete Rules, Relationship best practices

What is the preferred way to prevent a lookup-table record from being
removed when other records point to it? As Chuck noted here,
http://www.wodeveloper.com/omniLists/webobjects-dev/2004/May/msg00170.html,
to-many relationships from lookup tables to the records referencing them
are rarely useful in practice. And as Steve Sharman saw in the same
thread, such relationships can actually cause major performance problems.

If I correctly understand the EOModeler docs, however, you can only
enforce a "deny" delete rule on the source of a relationship. This would
seem to require defining the to-many relationship on the lookup-table.

To take another queue from Steve in that same post, is the Best Practice
to define the to-many relationship but NOT make it a class property? I
didn't see anything on http://wodev.spearway.com, the usual place I look
for this kind of advice.

TIA,

zak.