ok you are definately a cruise overpacker! lol. Here are my recommendations - one mom to another for a 7 day cruise.
The boys will have no problem wearing shorts more than once. - pack 3 pairs of shorts, pack t-shirts for each day, same thing goes for casual pants- 3 pair is more than enough, just pack a clean shirt for each casual night. Formal night - suit or suit separates, 1 dress shirt - 2 ties, dress shoes, 2 pair bathing trunks, underwear/socks, sneakers, water sandals, 1 pr
There really is no need to change clothes 3 times a day. In the morning, plan on wearing what you put on for the entire day until its time to get ready for dinner. For the daytime at sea that usually means swimtrunks and a t-shirt for the boys, shorts and a t-shirt over the swimsuit for the girls. For port days -depending upon what you are doing- shorts and t-shirt, if you are going to the beach, again throw a pair of short and at-shirt over your swimsuit.