big rocks and task of the day

Hi,

I would need to understand how to best use big rocks when they are promoted as task for a day.

Let's imagine than I have a "big rock" like for instance preparing a "trip to Nepal in 2018". I suppose that I would put this goal in my big rocks under family role for instance. There would be a lot of subtasks like plane, equipment, itinerary etc. ?

If this morning, I create a normal task like "preparing a meeting with my banker" this afternoon and since I believe I will have a bit of time, I promote as task my big rock "trip to Nepal in 2018". 

When I am done, with my normal task (bank meeting preparation), I click on done and it disappears with a little noise. However, when I am done with the part I wanted to do with my "trip to Nepal in 2018" task. What should I do ?

It is completed for what I wanted to do today but Big rocks should remain as I will need to come back and work another day/time on this project again and again. So I cannot select completed or it would disappear both for the day (which is good) but it will also disappear from my big rocks (which is not good) ?

However, if I left like that. There is no indication that I actually worked on it and also it seems that it will keep on coming back tomorrow.

Can you tell me how to do ?

Basically, the ideal would be to be able to select completed for any task of the day but just that if it is a big rock task, it would remain in my big rocks as well for another use.

Please note that I use the French version of you app.

Thank you