Alan Thicke Chose Brother Over Robin as Carter's Guardian

Alan Thicke made a decision years before his death, in which he chose his brother, Todd, over son Robin to care of his youngest son when he died.

Alan drafted a will -- obtained by TMZ -- back in 2007 that created a guardianship for then 10-year-old Carter. According to the document Carter's mother, Gina Tolleson, would become the sole parent in the event he died first, but if she died before him he wanted his brother to take over after he died.

The will references Alan's trust, which specifically lays out who gets what. The details of the trust are not mentioned in the legal docs.

The reality ... Carter is now 19, an adult so he's on his own.

The will appoints Todd as executor of Alan's will.