Patient’s family hired a private physical therapist in addition to home health PT. Advice?

Wondering if there’s a general consensus about this issue. It’s come up several times in practice for our team. Most clinicians, I know, feel quite uncomfortable having an additional therapist treating at the same time.

I had a patient canceled today, they hired a private family friend home health PT and wanted to reschedule my visit. It makes me uncomfortable but I’m wondering if the Reddit hivemind can help me articulate why: What exactly (If any?) are the problems that could arise? I mostly just trying to make sense of what the issues could be with this and continuing to treat this patient, potential liability, etc.

Any perspective is welcome.