I've seen a few requests for a Part Payment and POA allocation capability in Sage for CIS transactions yet all of them seem to be marked as "not planned". Rather than just saying that, could you explain your reasons please. From research into other programs, most allow for both Part Payments and Proforma Payments allocation to CIS and RC Invoices so this can't be a legislative restriction. Even a (previous?) partner program of yourselves allowed for this and posted this info directly into Sage, from what we were told when we spoke to them. It's not like you can't do this for non-CIS invoices VAT invoices.
Many Companies are now requiring the first order to be paid proforma, whether that be in full or in part so this is becoming more regular. Your own advised solution to this of deleting the payment on account/Proforma invoice and just repaying the VAT invoice at the same date when it comes in, has the same effect but is just a very messy and may I say, unprofessional way of doing it. Part payments are even more messy to reconcile.
So come on Sage, why the reluctance? Give us the tools we need please or as previously asked, at least an insight into your refusal to offer these functions please.