Kate Grace has made comments on other people's instagrams voicing support. So has Gwen Jorgensen. Though they didn't make a separate instagram post for it.
Kate Grace has not posted in support of Shelby, she has made generic comments saying things such as "it's nightmarish" and "it's devastating." Saying that the situation is a nightmare does not indicate support.
Yes she has posted in support, she's also posted hearts in other people's instagrams in support.