How old are the replacements? (newer ones can have way better ranges of motion – I have a client with a double hip replacement who has very good movement, including crossing over her center line as approved by her doctor but not do-able with older replacements)
What does her doctor say?
This is a case where I would request a doctor or PT note.
I have a client with a double hip replacement, and Nancy is correct about the age of the replacements. Mine should not cross over her center line or perform exercises that externally rotate/expand her hips beyond hip distance (think plié squat). Her replacements are about 20 years old. If your potential client becomes a client, I would consult with her doctor to get any limitations.
I’ve also had clients with a double knee replacement–same concept about consulting with her doctor, but I’ve not had any limitations there (each client is different).
Best to you,