I also find that Watchers (as mentioned earlier) provide good mobility/scheme running and then also let Sonnia use their LoS. Every time i use Samuel i never get the full effect of him, I probably am not using him well or positioned properly.
Francisco helps a ton if you keep him close to Sonnia.
Try to keep Sonnia out of ML, most people will try to get her engaged as soon as possible to prevent her firebombs from going off. (especially against Gremlins)