I don't get that either !! Usually with siblings if one gets it the other(s) usually do too ! I would think they would keep him home as well . I have siblings and have been amazed when one shows up but the space is paid for so I don't say anything !!
I usually send a light text like , " oh oh heads up , so and so isn't eating !! "
Doesn't always amount to anything though lol !! I always feel like the dcp are thinking I just want a day off !!!