Hi there!
I don't have a lot of experience with Wei Qi Booster in cancer, so you may want to reach out to the Chi Institute to see if it's a good fit. If you're feeling somewhat desperate, you could hedge your bets and use it along with the formulas discussed below.
HSA Protocol is potentially helpful for both hemangiosarcoma and malignant adrenal tumors, so it seems a good fit. It is rich in Dang Gui and Ginseng which, like Huang Qi (in Wei Qi Booster) are NK cell stimulants, helping to kill off cancer cells that way.
Xiao Chai Hu Tang is also appropriate as a general formula for abdominal tumors and has Ginseng. If using it (because you're unconvinced of pheochromocytoma or HSA), then pair it with an abdominal Blood mover like Ge Xia Zhu Yu Tang, which would give you some Dang Gui as well.
Hopefully, you see benefits with one of the above scenarios. Given the very young age (and thus a potentially long lifespan), it might be worth doing at least an exploratory rather than just assuming there is no possibility of at least debulking the tumor. Remember that herbal treatment of cancer is a 'numbers game'. The fewer the number of tumor cells, the easier the job for the herbal formula.
Lastly, please be sure to feed a real food diet. Particularly when herbs are being heavily relied upon, real food diets seem to help tilt the advantage toward the patient and away from the tumor.
Hope that helps!
Steve