Easily relate tasks

It would be really, really nice to be able to easily say "task A is related to task B". Today's use case:

"Hi Matt, Ugh I realized there was a mistake in the sampling sites I sent. One of the sites was mislabeled, and one of the UTMs was wrong. Here’s the corrected file. Please remake the maps (and sorry for the extra work!"

True, I could just re-open the closed task this is a follow up to, and add more time. Why that's not desired:

-- loses the date history --

This update request has different request and due dates from the original. If I change the due date of the old task to the new task it will make it look like the task took weeks longer than it actually did. This has big consequences as time-from-request-to-delivery is one of the metrics used when evaluating a person's performance.

--- breaks the task estimate vs actual effort hours relationship ---

What I actually want to be able to do is say "this new unforeseen change means an estimated extra 2 hours work", and then follow up doing the work and "...but turned out to actually be 2.5hrs". I can't do that by adding to an existing task. It _already_ has an estimated vs actual ratio in place (4hrs : 2.5hrs). If I fudge those numbers now, I lose the ability to use the data to refine future estimates.

--- Imagined implementation ---

Daily Use side: typing "task:123" (or task#123 or similar convention) in any standard field creates a hyperlink to https://my-domain.intervalsonline.com/tasks/view/123/. Would be especially useful in Time Description and Task Title.

Analysis side:

- Viewing tasks allows "group related tasks together"
- Reporting on time use allows "roll up related task totals"

There's other reasons to want to link tasks without the overhead of a project, but I don't have time to document now. I need to get on with fixing those sample sites!