Can you stop them from what they are doing?

No you can't but you can speed it up with Donuts to let them do another thing

Yes you can stop them from what they are doing. The only people you cat stop it lisa and homer. All you have to do ti stop them is place the Building that the person comes with and they will simply disappear from your village then go back to your inventory and place the building again and there will be your character as well
Hoped this helped

Yes you can stop them, just put their place of activity in the inventory and take it out again.
For example, if you have Lisa 'Doing Next Week's Homework' in the Simpson's House, just place the Simpson's House in the inventory box then take it out again. Lisa will come out doing nothing.
Hope this helps

Is there another way

You can not store the Simpson house. I already tried.

There is no way. You can't even store their house

Yes you can stop all except lisa and homer. To stop ppl you store the Building they come from and they go tooit will reset their task so you can choose a new one by the way they will spawn by the building stored wben replaced. You cannot do this to lisa as you cannot store simpson house. You cannot stop homer as he doesnt have a building. (this is unless you can store people in a task as oong as you can access it I havent tried it.