Labeling Legos

[IndoorKitty]

I have two nephews, Chief (3) and Deputy(1). Chief Nephew already has quite the Duplo collection. We gave Deputy Nephew a Duplo sorter box toy for his birthday. Apparently the addition of the sorter box has caused Lego hostilities to break out, so my sister is looking for a way to label the Duplos.

I think a dot of different colored paint on the inside of each brick/figure would do the job. Would the Sharpie paint markers work? Any experience? Better ideas?