Well, there is some research that suggests some brain training activities can improve scores on measures of working memory, but so far the effect sizes are negligible, except for literally improving performance on the exact tasks on which one trains. (E.g., one can practice memorizing longer and longer number sequences, which translates into improved ability to...memorize longer number sequences, and pretty much nothing else.) The data certainly don't, in my mind, justify the expense of the best-supported (and that's not really saying much) working memory interventions. You probably won't get better results than, say, playing concentration-type games with your kid. I think you'll get better payoff from using her existing memory strengths as an alternate route, than from trying to pour a lot of time and energy into stretching her working memory a little bit. For example, she has the kind of profile that will probably really enjoy something like "Times Tales" (
https://timestales.com/) for gaining fluency with multiplication facts, when it comes time to learn them.