It is perfectly possible to perform these services without comingling resources or funds. Attorneys, accountants, and other professionals routinely act as representatives for dozens of clients simultaneously without comingling issues. Your "rectal audit" would probably conclude in a couple of hours as you were shown the controls in place to keep activity segregated and you'd be forced to conclude that there is no comingling problem here.
Sure.....all above board....we trust everybody concerned, right?