Since you have not provided the details of headache, it is difficult to know if your nephew has migraine or not.
All headaches are not migraine. Migraine is a type of PRIMARY HEADACHE (meaning that there is no underlying structural pathology in the brain to account for the headache). It has strong family history, more common in young girls (although no age and sex is exempt), typically occurs in half of head (in children, it is often bilateral), has throbbing quality (described also as pulsatile/ bursting), usually associated with nausea and/or vomiting, lasts for hours to a day or two (usually), may begin with a feeling of not too well and occasionally with problems of vision or hearing and increases with activity (and so most of the patients want to retire into dark bedroom without much light and noise). HYPERACTIVITY is usually NOT a part of migraine. Rather, most of the patients become vegetative .
Migraine can be managed well by medication and other means. To abort the acute attacks drugs like usual analgesics, and certain specific drugs called TRIPTANS can be used. The choice and need of medication is decided by the neurologists/ physician. These drugs are to be taken on SOS basis.
Another line of treatment includes giving preventive drugs to prevent the recurrence and/or decrease the severity and frequency. Many drugs are available and again the neurologist/physician has to choose any particular drug keeping many factors into consideration. Since these drugs need to be taken regularly for fairly long duration of time, their side effect profile become very important ( a concern rightly voiced by you in your nephew s case).
I strongly advise that you should take a good opinion from a neurologist who has special interest in headache disorders.
The drugs which you have mentioned, namely Divaa (long acting Valproate) and Inderal (Propanolol) . both been indicated for preventive treatment of migraine.
Zapiz (a BENZODIAZEPINE) is not a headache drug and is usually used for stress (anxiety)/insomnia and epilepsy.
By and large, the consensus is that we should be using single drug for prevention of migraine attacks and if that fails (after a trial of at least 4-8 weeks), another single drug or a combination can be tried. Of course, if there is co-existent significant anxiety/ depression, that needs to be tackled as well. Many preventive drugs for migraine has overlapping actions (like Inderal which also relieves anxiety, Valproate which also stabilzes mood) and this can be used as a therapeutic advantage.
This concludes a brief overview of migraine and its drug treatment.