It's been a while since I've done one of these things! Opinions and constructive criticism are always wanted! I do plan on adding some interviews and test logs but I think I've made this a tad bit too long. Tell me what you think!
I don't think an interview would hurt and may even add a little to the story if done right. It could actually really help if sufficiently creepy. Test logs seem unnecessary though. Perhaps if you could get creative, they may work, but I don't think it would do any bad to exclude them.
As for the SCP itself, it's decent. Personally, I don't find the description of the "lackey" monsters quite as scary as the "leader", perhaps because of the darker skin tone, but I guess you'd rather not get into cliche horror aesthetics. The "leader" dynamic also somewhat lessens the horror for me. If the monsters' social structure was less understood, or maybe even instead if they were competing with each other, then I personally would find it a bit more disturbing.
You'll probably get a lot of opinions different than mine, though. This is just what I think.
Needs some cleanup for tone (like using the phrase "about the intensity of a nightlight"), and you need to use metric units when describing the monsters' heights. I'm also curious as to how there wasn't an earlier incident of monster-rampage if the family has had it since 19-whatever. Also, what happens if/when the subject stops meeting one of the conditions. I.e. if they remove the blanket after the monsters have manifested. Do they disappear? Do they attack the subject (the blanket summons the monsters, but protects you from them as well)?
Giving bearhugs to the unsuspecting since 1872.
It's still a work in progress (totally forgot to switch out the heights to metric) Though thanks for the idea of how its been passed in the family. I didn't even consider it. And I plan on adding some test logs to it. Thanks for the critique so far!