Reading one field through to another app

***complete rookie***

I have one app where the record is an Account, in which the account has an Sales Rep, which is a "member" data field. So all our Accounts are assigned to our sales reps. 

We have a separate app, for individual deals. Each deal is linked to an account using a "relationship" field.

I want to be able to enable the sales reps to sort and filter the deals (in the deals app), based on the accounts they are assigned to... however...

My [partial] solution: Add a "calculation" field to the deals app, and try to pull in the sales rep name from the linked account.  

String (@All of Sales Rep[0])

This reads it through as a string, which doesn't let me use "views" in the deals app, where each Sales Rep can see their deals by status.

So my question is: is there a way to copy over the "member" data field, so that the Sales Rep in the deals app can be used to filter on and create views? (potentially I have to use GlobiFlow or Zapier - we run both)