Expenses in diff currencies in one BU

Summary:

We have a requirement where in one BU, Cash expenses need to be submitted in Currency. And credit card expenses need to be always in USD

Currently if in system options under the BU, if allowed currencies are set to both USD and the local currency, User is able to select the currency field on the expense report, and there are cases where users are choosing local currency even on cc transactions. Its a training issue, but would like to know if there is a way to restrict the currency selection on the expense report

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