IMHO the "follow-up" task is the same as a "parent" (blocked-on) task: one that needs to be completed after the current one. It's just not exposed conveniently in the UI so nobody really creates parent tasks for follow-ups. That is what I suggested we should surface in T8794.

I think it is slightly different from "related tasks" as described in T8345. Related tasks are described as "neither task is blocking the other task". In my case, the "follow-up" task is just a classic "parent" task: one that needs to be completed once the current one is done.

Yes, we are not using Phabricator yet, although we should set up an instance very soon and migrate some projects to it to test it live.

Thanks! I totally get the restriction, in fact we'll likely do the same on our own instance.