If you want a different answer you need to ask a different question.
If you say "I want a referral to X" and he writes you a referral you can't really complain about that
If you say "I would like your opinion" then you will get his opinion which will be more along the lines of 'this is wrong, that is not wrong or I am not sure and will refer you.' But it might not be a referral if that is what you really want and not his opinion.
If you ask "I would like to know what you think about XYZ" and if you feel you want a referral and he does not suggest it you then ask "would you think it might help if we saw an orthopaedic doctor or would there be another option you would recommend?" then it opens it up for dialogue.
As a doctor I'll tell you the inside secret on how to get the best advice from doctors.... ;)
.... tell then the truth, tell them what you are worried about, don't be embarrassed or leave the thing out that is really worrying you, be open minded and ask them for their opinion. I won't say there are bad doctors out there or good ones never have a grumpy day (we are only human) but most of us respond well to good manners and honesty
In this case you say they are lovely so why not say "Hello Dr X, it is about DD, I was was wondering if a referral to Y for her might be useful and I would also like to know what you think might be the problem." That would be my dream patient!