Registration of visitors! (Moscow)

Dear All,

I hope you can help me with some questions.
I am very confused because I have very different information about this topic and I hope that you clear it up for me!
My parents will come to visit me. I am now organising all the visa stuff and I am searching for the right and correct information about registration/cancelation for visitor with a tourist visa in Moskau.

So can you help me? Here are the questions and some informations:
My parents will stay 6 days (4 working days). They will stay in our flat and do not book a hotel.
So do we have to do the registration? And cancelation?
How many days and working days do we have time to do this?
Who has to do the registration? We? Our landlords?
Where do we have to do this?

If you do not have any information, perhaps you can provide me with an other contact person.

Best regards
Veronika Kofler