1)
What should they do with the extra money?
1.
Rashi: What is good for you and your brothers, and like Hashem's will 1 , do.
2.
Malbim: Use it like the law of extra money 2 , like the Rambam writes in Hilchos Shekalim.
1
I.e. do not use it for something that displeases Him. (One can always buy more Korbanos. Does 'extra' imply a small remnant, too little to buy an animal? - PF)
2
I.e. if someone was Makdish money for a Korban, and he bought it for less than the amount Hukdash for it. Surely Malbim learns from "ki'R'us Elokachom." How does he explain "u'Mah Di Alach"? (PF)
