The "Third Order Secular of the American Congregation of Franciscans" was founded as part of the [Episcopal] American Congregation of Franciscans by Fr Joseph Crookston. When the American Congregation became the American Province of SSF its Tertiaries became part of the Third Order SSF. The Rules and related documents here give a picture of the character of the Third Order as founded by Fr Joseph.
There is a temporary glitch with those creating user accounts from Google hosted email addresses (including franciscans.org.uk and franciscan.org.au). Google blocks the email to complete the registration process. Please email me and I can fix it internally.