Finish to Finish Dependency

edited 11/01/23 in Smartsheet Basics

I have two tasks which have a finish to finish dependency. I know when both tasks started: Task A started 11/02 and Task B started 11/03. I know that Task B is expected will finish 3 days after task A finishes, so I would like to set a finish to finish relationship with a 3 day lag, and have smartsheets auto calculate the duration of Task B. However, when I try to do this, the predecessor is removed. the program seems to shift the start date while keeping the duration the same. Any suggestions?