I believe in the past we've said that if both players agree to make it official game canon then it is eligible but we've been through a lot of versions with mistletoe - does that match for you guys ihdrenieltinwateringcan ?
(though tbh it's kind of a loosey-goosey honor system thing; the language in the ac posts in dec/Jan is "IC comments on the mistletoe post may be used for AC." we're not following up with people to make sure they're not submitting non-canon threads, nor are we going to come at people if they submit an ongoing mistletoethread that they later decide not to