Assign one task to multiple lists
Subjects of names of lists do overlap very often in a way, so that a task could fit in one subject as well as in the other.
You may decide one day to put it in the one list, and not find it the next day, because you look for it in the other list.
To prevent this, you may put copies of the same task into both lists. But then it may be, that when having completed the task, you just tick one of them, because you forgot about the other copy.
I find this a very common scenario when assigning content to folders, categories, lists.
The most convenient solution is, to have instances of the same item, that can simultaneously be put in various places, so that the same item can be found under various subjects, while any editing will be applied to all instances simultaneously.
Apparently this had been implemented e. g. in Astrid.
Assigning hashtags is surely useful for other purposes, like filtering.
But as filters are no replacement for Wunderlist's lists, hashtags are no alternative for assigning tasks to multiple lists.
Please be so kind as to reconsider this essential feature.
I agree, adding a task to multiple lists would be great. I organize my tasks by projects but also by people I am meeting with on a regular basis. As I go through my day, I create reminder tasks that I could assign to a project and to a person list, so I can follow up next time I see that person. This is different than making an assignment as it still needs clarification first.
We really, really need this feature. It would help SO much and save SO much time. I have to add one specific item 15 times to 15 different lists. Would be so much easier if there was a way to just add to all the lists at once since it is the exact same item.
I have withdrawn my own votes from here, and moved them over to support this suggestion:
which represents much the same idea.