Multi-Period Accounting Impact on Sales & Use Tax

We've been attempting to leverage Multi-Period Accounting (MPA) and have encountered challenges with invoices:

a) that include sales tax on lines that do not use MPA as well as those that do

b) that are split (at line level) between capital and expense, with sales tax applied to both

c) that are matched to Purchase Orders and not commonly analyzed for accounting impact when matched, as this is assumed to be done when the underlying requisition/PO is approved

d) that are subject to use tax

e) that cover service periods that started in a previous accounting period (e.g., an 01-May-13 invoice for service period that covers the period 01-Apr-13 to 31-Mar-14)