How to update RTI FPS (Full Payment Summary) with On Strike from a Strike absence

Summary:

We have a Strike absence type/scheme which deducts pay for the duration the employee is on strike, however we need to pass this information to the RTI FPS (GB legislation) to indicate the employee is on strike to HMRC; currently the Statutory Calculation card for each assignment is being amended manually as a workaround, but there surely must be a way to feed this information to the Statutory Calculation card? I note that in Absence Certifications, there is a seeded certification called 'On Strike', which cannot be amended directly, but according to the detail on it creation is triggered