Cash Tally in Shared Service Organization

In our client requirement is below, please let me know any one worked in this kind of requirement and if you have automate solution let us know. Welcome your thought and solution.

 BTC – Operating Unit is Shared Services and it is centralized operation for Cash. BTC main cashier pay the cash on behalf of other company (other OU & LE) as well collect the money on behalf of other company and there is only one Cash Box.  Due to this Negative cash balance in one company and Positive cash balance in another company and manually passing contra entry for the cash as well as intercompany entries. As per their requirement they would like to automate solution that whenever the BTC pay or collect the cash, automatically system should pass intercompany transaction and contra entry for cash as well as Cash