The secondary afghan is on the lap of Gabriel in 1840 every time we see him in his wheelchair. The episodes I've noted are 1111, 1112, 1146, 1148, 1154_5, 1156, 1158, 1159, 1160, and 1161, but Gabriel appears more than that, so clearly I was negligent in my noting.
Also we see it on Lamar Trask's chair in episode 1145. We know they had other blanket entities that they could use, so it seems strange that they used this particular afghan, but maybe they just grabbed whatever was closest to hand.