While Tong Ren can certainly be used (but, yes, it would have to be tailored to her specifically), I’ve found acupuncture a critical part of treating POTS. I’ve certainly treated it and with good results, and I imagine that most practitioners who have been in practice for 5+ years have seen it as well. It can, however, be a bit of a lengthy process and require some ongoing intervention in some cases. So if she were to go the acupuncture route she should plan for regular treatments for at least 3 months. Ideally, she’ll see a practitioner in her area who also practices Chinese herbal medicine. Herbs may not at all be warranted in her case, but if the western diagnostic tools have found nothing, there is a chance that an herbal quotient to the process may be appropriate.
For Tong Ren, yes, generally somewhere in the vicinity of low blood pressure and tachycardia points. If you are able to physically inspect the points you can make a list of those you are finding, then simply palpate them on her and choose the ones that seem the most sensitive to her upon palpation.