Read the code; former first ladies do NOT get SS proetection if they aren't married anymore; Lady Bird gets it by act of Congress, but she will be the last one.
And Chelsea is NOT entitled to it, period. No other child of any past president has EVER had it past the age of 15. Jackie Kennedy refused it for HER children and paid for theirs. Of course, the Clintons would NEVER do that.
The SS contingent that the Clintons have is HIS.....and he has to "give" the agents to Hillary and Chelsea, if they get them.
Authorization
Today, the Secret Service is authorized by law to protect: the President, the Vice President, (or other individuals next in order of succession to the Office of the President), the President-elect and Vice President-elect; the immediate families of the above individuals; former Presidents, their spouses for their lifetimes, except when the spouse re-marries.[My words ... this means Hillary unless she remarries]
In 1997, Congressional legislation became effective limiting Secret Service protection to former Presidents for a period of not more than 10 years from the date the former President leaves office. [My words .... A new law like this would start with the next President.]
Children of former presidents until age 16; visiting heads of foreign states or governments and their spouses traveling with them, other distinguished foreign visitors to the United States, and official representatives of the United States performing special missions abroad;
Major Presidential and Vice Presidential candidates, and their spouses within 120 days of a general Presidential election.
Actually, Barbara Olson points out in The Final Days (a Christmas gift from Mrs. RightRules) that x42 signed an exec order on his way out the door giving Chels SS protection for six months. No word on whether the contingent was stolen along with all the other goods Bill & Hill left town with.