If someone only has one broken piece of bread, can he borrow from his neighbor two whole challas and make ha'motzei on everything together (the 2 challas and the piece of bread); however not eat from the challas and give them back to the neighbor?
I'm essentially asking if there is any "advantage" of making the bracha of ha'motzei with lechem mishneh even though one will not eat from the lechem mishneh at all.
Relevant information: We find in Hilchos Pesach (Shulchan Aruch Siman 482 Sif 1 in the Rema) that one who only has 3 whole matzas to use for both nights of Pesach he should break one of them and make all the brachos however only eat from the broken piece of matzah, leaving the whole ones for the 2nd night. Could this apply the whole year? Or perhaps Pesach is different since according to some Rishonim (at least one, the Rif?) a person makes ha'motzei on the broken piece of matzah.