is this legal?

In the United States it is legal for her to buy, flip the house using her own real estate company. If she is the agent listing the house she must disclose she is the agent. If she is not, then it is at the discretion of the agent listing the home. Most agents will disclose because the person buying the home will find out at closing.

I suppose it depends on where you live and what the law is. But, it's probably legal, why not? As long as she follows the laws, she can buy a house, even using her own company.

Doesn't that depend on which country she lives and workes in? I can't possibly think the whole world has the same rules on the matter...where is she from?