Multi-Period Accounting - Collection at time of requisition

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With prepaid cloud services accounting changes coming quickly we are looking at using multi-period accounting. However there appears to be a gap when trying to do this with PO backed invoices. It appears the functionality should be available at time of requisition for the user to enter the period of the service, and the account generator to create the amortization account and the expense account. 

Anyone have ideas on how this could work with the requisition through to invoice to minimize accounting needing to reclass lines or other manual work arounds?