um.. the "easiest" way to do it would be the noble with the spare healer have to issue a command... and only if he's got no wounds/wounded.
then the game would randomly select 1 other noble with wounded troops and add that healer's effect to the target noble's healers (who's stationary in the region)...
i assume there's some sort of diminishing return for healers anyway? so any cascade would probably not be all that significant.
