Illegal but depends on who the family member is and their ability to trust you even when you make a substantial loss. I trade on my husband's retirement a/c and technically that is also illegal but psychologically it is not.
there’s only one answer to this question and lpope gave it. Get a power of attorney from your broker. They do this all the time and will likely have a boilerplate form. This allows the broker to talk to you regarding the account. then have a side agreement between your family members and you. It should be written down but it doesn’t need to be written by a lawyer assuming your family and you love each other and really understand what you both are getting into. If you both do not understand the risks and motivations involved then you shouldn’t be considering managing their money for them in my opinion.
A lot of BS here. A lot of brokers offer the form to designate another person (even stranger) to be your trader and have full trading right. There is nothing against the law as long as the paperwork is done. On the form, there is a section of the liability from the broker. The broker is not responsible for any legal issues arising from the designated trader arrangement. This is the same as the legal "power of attorney".
The only thing you'll have to get careful is if both accounts trade the same instrument at the same time. Try to avoid the impression of collusion of trading from two or more accounts.
Not for friends and family and under a certain asset limit. For family I don’t even think an asset limit exists. power of attorney doesn’t require licensed advisor. Collecting fees does in certain cases.
Debating theory is great but in practice, that is not what happens. Account will be frozen immediately. Speaking from personal experience.
This is true. I once traded for my friend after we both signed that form(power of attorney)and sent it to broker.