Complex Formula Based on WBS Formula

I'm trying to find a formula that will help me to auto-calculate the Start Date, Due Date, and % Complete based on an existing formula for Work Breakdown Structure (WBS) in a Gantt Chart. I have a project plan/gantt chart that has three levels of detail in the WBS (1, 1.1, 1.1.1, etc.). Here's an example of what I'm trying to calculate: If WBS = 1, return the earliest Start Date of all Start Dates with WBS = 1.X; If WBS = 1.1, return the earliest Start Date of all Start Dates with WBS = 1.1.X. In other words, I only want to enter the Start Date in the lowest level (Task level) (e.g., 1.1.1) and have the higher levels (e.g., 1.1) auto-calculate. I'm hoping to figure out the logic/formula and apply it to Due Date and % Complete. In addition, I want to be able to add/delete rows without having to manually update the formulas. To explain, the formulas I'm using to calculate WBS auto-update when adding/removing rows; however, I found these formulas online when researching gantt chart templates, and am not sure how to edit them to be applicable to Start Date, Due Date, and % Complete.

This is great - thank you!

Hello, if you put it into an excel worksheet, you get the message, you are using too many arguments.