Update Related Records And Remove Duplicates

I have two tables, one is of departments, and one is of people (with a FK denoting what department this person is in). Now consider the fact that there are duplicates in the departments table, and I would like to remove these duplicates. However, the duplicates have related records (in the people table). So, before removing the duplicates, I must update the FKs in the table of people (this is the step I'm having trouble with).

Here's an example:

As you can see, the "Sales" department is there twice. And both have a related record. What I want to do is:
Update all DepartmentIDs (in tblPeople) to not point to duplicate records. In this example, that would be PersonID 2; Joe. His DepartmentID should update to "1" (as both "1" and "2" are "Sales").Delete the duplicates in tblDepartments (in this case, DepartmentID 2, "Sales").

The second step is no problem, it is only the first I am struggling with.

Also, the example posted here is just an example, the data I actually need to do this for is significantly more complex and there are many more records! In the attached database:

qry1: Simple query to find all duplicates (just used the query wizard)
qry2: Just the first row of each duplicated departments (duplicates that shouldn't be deleted). In the example above, this would be the "2", "Sales" row in the tblDepartments table.
qry3: Basically all qry1 rows that don't appear in qry2
qry4: All qry3 values, and their respective qry2 value.

This is what each of the (soon to be deleted) duplicate values' related records' DepartmentID should be updated to... There's no simpler way to phrase that, so using the example above, qry4 would return "2","1". This indicates that all people with a DepartmentID of "2" should be changed to "1" (so we can subsequently erase the department with the ID of 2.

This is as far as I have gotten. My next step is: Update all FKs in tblPeople based on qry4 (You can't set an update query's criteria to pull from another query, nor can you use the second query for the update value... or maybe you can, but I don't know about it).