TL;DR: Force the parent item's start to match the earliest subitem date and the parent's end to match the latest. The parent always exactly bounds its subitems — no slack, no overruns.
What this does
Two complementary recipes work together:
"Ensure that date/timeline of an item always starts at the earliest date/timeline of its subitems"
"Ensure that date/timeline of an item always ends at the latest date/timeline of its subitems"
Together: parent timeline = exact bounds of all subitems. If a subitem extends beyond the current parent end, the parent end shifts forward. Same for start.
When to use it
Strict project tracking where the parent should reflect actual work, not aspirational dates
Avoiding "parent says ends Friday, but a subitem actually runs to Monday" mismatch
Roll-up reporting where you need accurate project bounds
Before you start
Date columns (or Timeline column) on subitems
Date columns (start + end) or a Timeline column on the parent
Set it up (4 minutes — two automations)
You'll create two separate automations: one for "earliest start," one for "latest end."
Automation 1: parent ends at latest subitem date
Open Automate → Create.
Copy the first recipe text above ("…always ends at the latest…") and find it in your board's automation center, then click Use Template.
Move a subitem date past the parent's current end → confirm parent end shifts forward.
Move another subitem to a date earlier than the parent's current start → confirm parent start shifts backward.
Common gotchas
Two separate automations are required — one for start, one for end.
Don't set parent dates manually — the automation forces them. Subitems are the source of truth.
For Timeline columns, use the timeline-specific recipe variants.
Different from the parent timeline rollup — that one feeds a Timeline column. This pair forces exact bounds across separate Date columns OR a Timeline. See Roll subitem dates up to the parent timeline for the rollup version.