Is there a way to process webhooks one at a time?

I have a webhook set up to kick off a scenario any time a project status changes to a certain status. Within this scenario, a data store is accessed that houses project numbers available for use depending on project type. The end of the scenario increments the available project numbers so that there are no duplicates.

The issue is, if a user changes the status of multiple projects at the same time (for example, all projects within a program), the scenarios runs too quickly and assigns duplicate project numbers because the data store is being accessed before the other scenarios complete (and increment the project number for the next scenario run).

Anyone have ideas on how to force Fusion to wait until one webhook completes before allowing the next to process?