I'll jump in as a pharmacist. State laws vary on what is allowed & what is not allowed as far as prescribing for family/friends. Physicians often don't realize that prescribing laws are governed by states, not federal laws. Even though we have federal controlled drug laws, if a state law is more restrictive, the state law overrides the federal. That is the case here in CA & I know it occurs in TX as well.
In my state, CA, you must have a professional relationship to prescribe for the patient. In state board opinion & case law, that translates to having seen the patient in person, have a current chart within your office/clinic/place of practice, etc...
However, those laws are in place to prevent online prescribing and the rx I've known to be subpoenaed (sp???) have been those for excessive numbers (numbers of rxs) or quantities of controlled drugs, or when a pharmacy is "caught" sending rxs over state lines. Remember - no one tracks noncontrolled drugs except insurance companies, but The Dept of Justice "sees" each controlled drug the moment it is filled.
Now, given all this, I fill for prescribers family many, many times - particularly at this time of year. It is professional courtesey on my part & those prescribers do not abuse their prescriptive rights. Their children go to pediatricians, spouses use their own physicians & the physicians/dentists themselves normally use their own providers on a regular basis. However, when it is a holiday and the grandparents come & forget their medication, the wife develops a UTI or a child now has a full blown ear infection, I'm very comfortable filling an rx for a prescriber & in 30+ years have never had any issues from any state agency.
The whole DEA# thing is changing (thankfully!). The DEA # was only required if you wanted insurance coverage. Cipro generic is not so expensive anymore, but when it was brand only (like Levaquin or Avelox is), insurance was important. The only way an insurance company could identify the prescriber was by the DEA#. That was the only unique & non-repetetive # available. License #s & patterns are not uniform state to state - so you'd have a dentist in WI having a license exactly the same as a podiatrist in FL. In CA, we stopped allowing institutional use of DEA's outside of the institution about 8 years ago.
Now, however, we have the NPI #. This also is a unique & non-repetetive set of #s which identifies each prescriber, clinic & pharmacy. We will no longer be using the DEA (soon hopefully - was supposed to be this month, but was delayed). We have finally convinced the insurance companies that having prescribers DEA #s so ubiquitous allowed them to be easily "found" & used without the prescribers knowledge. So, in the future, your DEA # will only have to be used for controlled drugs - not the cipro example. For insurance, your NPI will be fine.
So - long explanation, but each state has its own rules for presribing for family. Each pharmacist within the state use their own judgement on how far they're willing to "bend" the rules. If you try to call in an rx to a different state & the pharmacists says you can't, thats just the laws of that particular state.
There is a long thread on this issue a year or so back. Perhaps Dr. Cox can find it.