Thanks moteus that worked! I had to run 2 commands using Advanced, Command menu before I started seeing it work:
reloadxml
luarun /usr/share/freeswitch/scripts/call_flow_subscribe.lua
Now when my yealinks refresh their BLF subscriptions it updates. I do still have to figure out why it clears it first though, which is odd. But will worry about that later!
[update] Omg, I dunno how I missed this. But call flows should start with "flow+" then the feature code example: flow+*7003
The phone no longer clears it, and no longer wakes up every time it refreshes subscribe.