We have Cape Air coupons which, according to their website, can be combined with a separate ticket on United, Jet Blue or American. We called several times and were told the software for the two former would allow this, but not American's software.
Coming down, American could not check our bags through and we had to pick them up and recheck them, which became tricky when our arriving flight was delayed. Made worse because I had frozen steaks they made me completely unpack; only carry food if your bags can be checked through.
We're going back on United, so I enquired at Cape Air Beef Island about checking our bags through. The two people working the desk said it is not possible, regardless of what their website says. YMMV.
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