Flexible furlough calculation - complex

I have a furlough calculaton needed asap and would welcome invites from people who are confident in these. It involves a variable pay employee, who is flexibly furloughed, a pay period which covers part of July and some of August, and holiday pay (which needs 80% claiming under the furlough scheme and then topping up by the employer). I am looking for a breakdown of the calculation (the software in use will not deal with this level of complexity). There is no requirement to calculate the NIC and pension element as that can be done by ourselves. It is for one employee only. HMRC, and the CIPP have been unable to assist as have the software provider so this does require a manual calculation by an experienced individual. Please only place a bid if you can complete this task manually, and not simply looking to run it through payroll software.