A Table calculation would fix this issue. I went ahead and attached my work, but really the only thing you needed was to create a field as such:
This repeats the last non-null value. Thus the addition of the [Amount] and new field would result in the appropriate overall total amount.
Hope this helps!
This works exactly how I wanted it. Thank you!
The only minor issue I will need to investigate now is how to handle the Manual_Amount value if the date range I am viewing in my chart does not have a starting Manual_Amount value. The result for this calculation will then be NULL. In my example, imagine if the Manual_Amount value for August 30th was NULL, then all the dates up to September 3rd would be NULL. Thus the Overall_Total_Amount would add a Manual_Amount value of zero.
Let me know if you have any thoughts on that.
Otherwise, once again, thank you for your help!
revise the calculated field as follows but first create create a parameter (NewStart). Then test by filtering your chart with start dates having null values. The parameter will control the value you want to set should your series starts with 0 manual value.
if(first()=0 and isnull(sum([Manual_Amount]))) then sum([NewStart]) else IFNULL(SUM([Manual_Amount]),PREVIOUS_VALUE(SUM([Manual_Amount]))) end