Hard to know what your goal is. You are saying you had Adderal in your system and you think it will go into your wife's system via sex and cause her to have it show up in her urine test for drugs? And that whomever does her drug test will know she has been prescribed roxycodone, but not want her having Adderal and for that reason, she is considering taking along a vial of fake urine to which has been added only roxycodone so it would look like her usual urine profile? How do you know Adderal would be in her system? Has a doctor told you that you can give her Adderal via sex and that it would be in a significant enough concentration to appear on a test?
It isn't clear exactly what you're trying to accomplish, but faking a blood test for any reason is a very bad idea. Her doctor could discharge her from his practice. She could lose her pain management doc and any pain meds she is taking, and might have difficulty finding a new doc.
The best policy is to be honest with the doctor.
Why would having sex with your wife effect her urine test? One has ZERO to do with another.
And altering the urine in ANY way will absolutely cause her to fail.
Having sex does not transmit adderall to your wife's urine. Using fake urine WILL get her dismissed. I suspect you and she are trying to pull some scam, and I don't condone that, period.