Oracle EBS - Service Cost Accounting - Applying statistical journals at an "activity" flexfield leve

We utilize Oracle EBS as our county system of record.

We are in the process of rolling out "activities" as a flexfield in order to group operating costs within specific activity/ service pools.  For example, we are trying to segment costs for a animal resources department between an adoptions service line and a pet licensing service line.  So far, the "activity" flexfield appears to facilitate that grouping of costs.

We run into a problem when we try to apply statistical journals against the "activity" flexfield.  Essentially, we can only define the units of measure at the natural account code level (i.e. office supplies expense, postage expense, maintenance expense) but we would like to apply the statistical journal to all costs at a rolled up (parent) "activity" level such as the pet licensing mentioned above.