There are a lot of people who equate soccer with running. I would disagree with that. Not all running is the same.
There is warmup, recovery between repeats and cool down. So, you do that at a pace of 10-12min/mile. Some people add it to the total, others don't. You have the repeats which are definitely harder miles. Adding easy and hard miles together and coming up with a number can be confusing. Say your daughter runs a total of 35 mpw and she does not have the results she needs. I would not necessarily increase the miles to get better results.
Playing soccer, you are likely to develop one larger leg and bigger calf muscles than pure runners (unless you are a #9). That modifies your running mechanics and, during running practice, you may have to unlearn certain things.
I think there is a lot more wear-and-tear in soccer than in running. So, you run about a 5miles over a 90min game at a competitive/academy level. That takes a toll. Doing a 5mi run at an average pace that is faster than the soccer game average pace, you end up with a much more reasonable recovery.
30mpw running is not equivalent to playing 6 soccer games per week regardless how hard you run those 30miles.
I have coached my kids to multiple national medals and I can tell you that they run less than that. I have also seen kids who run more and have not gotten hurt so the # of miles is not really as much as people make it to be. So, my advise is to use your judgement as to what works for your own daughter. Don't just go on a formula at the expense of monitoring her. If you see something wrong, then change the approach. There seems to be this broad obsession with tracking miles and ignoring everything else. Don't fall into that trap.
This reminds me of one of my favorite movies "Better Off Dead" and a character named Bugger: "Go that way really fast. If something gets in your way, turn." Oddly, he did not advise to "stay on course".