Hi Kapil,
We should never let SAP punish ourselves 
let's fight back
Do you need to post the charges (additional flow) at deal date? If not, you could test posting the other flow at n+1 and then, whenever necessary, you should be able to reverse only this flow.
I know this is not a perfect solution, it's more like a workaround but I don't see any other way to avoid reversing the entire deal in such situation.
Regards,
mcc