2yo hates a duvet!

[AmieB]

Our DS is 2yo and for a while now we have put a toddler duvet in his cot every now and again to see how he reacts/whether we can make that transition (he already uses a pillow), however every time we do this he is absolutely hysterical! Screaming to the point where he could (but hasnt) been sick. Of course each time we pack the duvet away and return to his beloved sleeping bag.
Although we are in no rush for this, we would like to get both him and his older sister into bunk beds, I'm just wondering if anyone has any tips or is it just a case of trying every few months?
We've let him pick a duvet cover which he loves but once it's on his bed it makes not a blind bit of difference. He loves his sleeping bag and has always tucked himself into it and snuggled into it which I think is a comfort to him, I've tried putting the sleeping bag into the bed with him and the duvet but he still screams blue murder.

Any tips appreciated:)

To add to this -

We only want to get DS and his older sister into bunkbeds as we are military and really need his room as a guest room for when family stay.

X

Is there a reason why he can't use the sleeping bag in the bunk bed? My DD used hers as she was able to take it off to get up /out of bed.

Just leave the duvet laying around for now. Maybe in the living room or on the bedroom floor. It can gradually migrate to the bed

Sleeping bag with legs? Slumbersac do them for all ages.

Sheets and blankets tucked in tight? Sounds like he likes a bit of restriction to feel safe

Why can’t he stay in his sleeping bag?

Mine didn’t like the duvet (not to the point of screaming, but just kicked it off / wriggled away) and much preferred to fall asleep without a cover. Fine in summer but I just made sure he was well wrapped up in winter. The duvet stayed folded back at the far end of the bed, and when I checked on him before going to bed myself I would fold the duvet over his feet and legs if he felt cool. It usually stayed on unless he was awake early and bored, when he’d push it onto the floor.

Agree just leave it lying around the room as a blanket, or folded at the end of the mattress

Happy for him to stay in a sleeping bag, just kind of thought okay at some point he should be sleeping with a duvet and pillow? Like I said, no rush, just looking for any tips.

Thank you guys, might actually use the idea of having it folded at the bottom of his cot and just gradually introducing it :)