Try spraying that ink stain with hair spray, it worked on the pockets of my husband’s shirts. Then I bought plastic pocket liners and he put his ball point pens in those.

I would put extra soap or stain solution right in the interior of the washer-not sure about home front loaders but the laundromat ones tend to leak the extra amount out if the door is open, so I just put inside the washer now. As for adding extra water you are sick with what the washer gives but set for the biggest, heaviest & most water used load. Like the extra heavy bedding setting which is what you definitely want anyhow because it takes longer to make sure all the bedding soaks up the water. Extra rinse if you have that. Wash a second time or a third time if really really needed but if you have an extra rinse & spin only option use that with your vinegar or fabric softener. Sometimes there is just a spin or extraction setting & that is great for spinning out extra water to cut down drying time.

Not sure about silk duvets-never had one. I have never heard of a feather duvet though. Where did you get a feather duvet from?

It kills bacteria to clean them without the wear and tear of washing :-)