For some reason..it's cheaper to fly from grand rapids,mi to san francisco than from dtw. So I found flights that leave from GRR and make a stop in DTW. and when returning they depart from SFO and make a stop in DTW before going to GRR. (why is it cheaper? I'll never know). Anyway...would it create a problem if I completely skipped the GRR flight and hopped on right from DTW? Probably a stupid question...but I never know the rules Thanks!