How do we submit a standalone FPS for HMRC Appendix 8 Agreement?

An Appendix 8 Agreement requires you to submit an annual FPS to HMRC for earnings accrued in the UK by offshore employees, for short periods of time, but paid via an offshore payroll. This is independent from standard PAYE payroll processes. How do we do this in Fusion when those employees are paid by an outsourced payroll provider? Essentially we need to record earnings and report them to HMRC via an annual FPS submission in Fusion, without actually paying them through Fusion. Is this possible? Does anyone have experience of doing this?