I was looking at the following question, which appears to suggest that multiple indirect effects can be added together to calculate a total indirect effect. Multiple mediation analysis in R
But reading the abstract of this paper leads me to believe that there is a way to calculate the total indirect effects all together, and that calculating them separately and adding them together may be incorrect.
What would be the proper way to calculate a total indirect effect?
If I want to know how much of CY is not explained by and indirect effect of A or B, could I subtract ACY and BCY from CY?