How to link the due date of a specific task or subtask into a custom field of a portfolio

[Tetsuo_Kawakami]

I revised the original post. so it doesn’t make sense below.

I recognized this post is wrong.
“specific due date” changes day by day.
To avoid that, we need to append a date custom field for dummy in projects and portfolios.

I’ll revise this post later.but I write a summary below;

1. Append a date custom field named “dummy date” to both projects and portfolios
2. Set any date as you like to “dummy date” for the specific task.But you need to set the same date in a portfolio.
3. Change the definition of “due date - today” to (Due date - dummy date)/1440+0
4. Change the name of “due date - today” to “due date - dummy date”
5. Change the name of “due date - today2” to “due date -dummy date2”
6. Change the definition of “specific due date” to DateAdd(dummy date,Rollup(due date - dummy date2))