the Fatwa Department Research Committee - chaired by Sheikh `Abd al-Wahhâb al-Turayrî
As long as you fulfill all of the conditions set by the company for being entitled to receive the commission, then if you do so as you describe above by having the family member present and registering on the site on his or her own, then – Allah willing – there should be nothing wrong with it.
The reason we say this is that by having your family members visit the site on their own and register, you have fulfilled the service of actually referring them to the site, which is indeed what the commission is being paid to you for.
You must be careful to comply with all of the guidelines set by the company to be eligible for the commission. You must not yourself, or have anyone else, deliberately misrepresent information so you can receive a commission. That would be fraud.
Fraud is a sin. Allah says: “Woe to those that deal in fraud,- those who, when they have to receive by measure from men, exact full measure, but when they have to give by measure or weight to men, give less than due. Do they not think that they will be called to account on a Mighty Day, a Day when (all) humanity will stand before the Lord of the Worlds?” [Sûrah al-Mutagffifîn: 1-6]
Any money earned through fraudulent means will be unlawful wealth.
And Allah knows best.
Source: Islam Today