As per my understanding, following are three list you are working with.
- Employee List: Keep a track of Unit Manager and Employees within it.
- New Request List: All the new request are logged in here by end users.
- Requested Orders: Once the Unit Manger Approve a request, automatically a order must be created here.
Base on above problem, I am using an assumptions here that in Employee list contains the Unit Manager
column is single-select People only and not enforcing unique values and Staff Member
is multi-select People only column. Also, I am using a lookup column in New Request
from Employee
list to get the manager. If this not the case, in MS Flow, where I am using SharePoint Get Item
you can modify it make a REST API Call to SP
to get the right manager. Remaining logic remains same in MS Flow.
For reference use the URL to see how to create approval workflow in MS Flow.
Overall MS Flow:

Step 1:
I added the MS Flow to New Request
list. The flow will trigger as a new item is created in this list. The Employee
list and Request
list schema is following, while the order list in my case contains only Title column.


Step 2: Here I am using the trick to get the Manager Email ID using lookup column. In case you are not using lookup, either use SharePoint Get Item
action or Send HTTP Request to SharePoint
. The flow configuration is following:

Step 3: Once we have the Manager Email ID, we need to use Start an Approval
MS Flow action. Except the Assign To
all other values are filled using New Request
List.

Step 4: Now add parallel branches based on approval
condition we can make the decision. If the Approval is 'Yes' we have a set of logic to create a new item in Order list
and send confirmation
mail, otherwise send the mail to initiator saying request rejected
and adding Unit Manager comments
.

This completes our approval flow. On Approve we are adding a new item to Order
list, if rejected we are just notifying the user. Also to note, this will trigger only when a new item is created. If user modifies the request nothing will happen. They need to submit a new request. We can modify the logic by triggering flow on when item modified
.