What is an easy way to put a down comforter inside of a duvet?

I take the top two corners of the comforter and put them in the duvet. I then take 2 large safety pins and pin the duvet to the comforter. This way I don't lose those corners and I finish putting the rest of the comforter inside the duvet. I then pin the bottom two corners and I give the whole thing a good shaking. I sometimes have my husband help me shake the whole thing because it is a king size. It's still not easy but at least I don't have to start over because I lost the corners. Then I just remove the pins and finish making the bed.

Yes, a duvet is a comforter and the cover is a duvet cover. Here is the magic way to do this (I also need to put one on but will wait till tomorrow) Lay your duvet cover, INSIDE OUT on your bed. Lay the duvet on top of it. Start rolling from the top of the duvet plus cover, down to the bottom. Fold the duvet/cover over each other and roll back to the top. You should have enclosed the whole duvet in the cover and the cover will now be right side out and the duvet will be inside it. It probably will be easier to do this if you lay the duvet cover with the opening towards the head of the bed.

Lookit up on u-tube. It's a kewl way to roll it on.

https://www.craneandcanopy.com/pages/101-how-to-put-on-a-duvet-cover

Turn the duvet inside out, lay it on the bed flat. Next, lay the comforter on top of the duvet. Fasten the comforter in each corner, and 2. on each side. Their are clamps that look like clothespins, you attached at the spots I mentioned. Pull the duvet inside out and zip up the bottom. The clamps can be purchased at any department store or Bed,Bath, and Beyond. Good Luck!

Thank you so much for all your replies. They all sound very interesting and feasible. I will print them and try them all. Again thank you.