Automation to create copies of a newly created record for each user in a certain user list field

I have a table that I want to create a record in, and then automatically duplicate the record for each user in a user list field.  

So if there's 10 people in the user list field, a total of 11 records will have been created, 1 master record, and 10 duplicates with the user field having a different user from the user list field. 

The case scenario is a manager needs to create a record in a table for monthly drills.  When he saves that record, a new duplicate record is created for each of the 10 people in the user list field.  The only difference is a user field in each record, one for each user in the list. 

This is all done from the same table, everything is in place except creating the duplicates.

I've seen something like this done using webhooks I believe, but it was awhile back and I can't refer back to it.

Thank you!

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Dana Hauser
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