how to update the value of an assignment flex field within a workforce compensation plan

Summary

is there a way we could update a value in a flex field within a compensation plan

Content

We have an active workforce compensation plan in which we are using for promotions. I have a fast formula which is calling out a value in an assignment dff, but i need to update that value as well. is there a way we could do that in the worksheet? when i post the worksheet to HR, i want the value in the worksheet to also update the value in the assignment dff? Thanks

Version

21A