If she didn't like natural calm, most of the other choices taste even worse, sadly. We used mag glycinate from kirkman, and that's my favorite form, but it doesn't taste great. I taught my little guy to swallow small capsules about 6 months ago (he was 2.5, ASD, and non-verbal, and it was actually really easy - I started with kitten sized teeny #5 capsules and worked up to #3 capsules - I dip them in maple syrup and he happily swallows them - about 20 a day at this point, I load all his supps, enzymes, and probiotics into them now).
If she's sals sensitive, you'll also want to look at supping molybdenum and P5P (active form of b6) - the P5P helps the mag get used, and those three help with the pathway that processes salicylates. P5P tastes bleck too, so the capsules really help with that as well.
Probiotics, we're currently on the d-lactate free strain for autistic kids from custom probiotics. I've only been doing them a short time, but DS reacted badly to the FOS and d-lactate producing strains (like l. acidophilus) in most probiotics.