I believe it is perfectly proper for DCAA and DCMA to request written authorization from a contractor regarding a consultant handling government compliance issues such as incurred cost submissions and accounting system audits.
What I do not think is proper is suddenly demanding the authorization in hopes of getting around the consultant and thinking the client is more vulnerable and less likely to discuss compliance on their level (or above).
One recent example is an auditor demanding the contractor redo the Schedule I to make it easier to complete a cumulative cost schedule. She admitted to this in a telephone conversation and came to realize that this would require complete resubmissions to include new Schedule N for perfectly adequate and compliant submissions.
This same auditor today (different client), after numerous email correspondence and a telephone conversation that helped her locate the contract briefs in their proper places in the submissions, demanded the authorization after I asked her to expand on her statement “and negative responses were not provided for Sch M”.
The authorization issue does not come up often and usually DCAA is satisfied with a client email. I have a template I developed in conjunction with a client’s counsel I use for more formal occasions and this I send to DCMA as DCAA is their consultant.