i am sure you already have the answer you need, and your parents' routing is certainly more exotic than anything i have ever done, but i did 2 FF trips last year that were open jaw: DL: DFW - CDG and back from MAN, and AA: TUS - PTP then ANU - PHX (I arrived in ANU on a sailboat, and had never really legally LEFT Guadaloupe, or entered Antigua for that matter....there were some raised eyebrows at customs, but I pretended not to speak english [despite the american passport], and they let me though....and the less said about all that, i am sure, the better)