It's something we'll be working on definitely; both of the boys have been very good at helping out with Moshi so far -- we just all sat down outside the shower and each did our part to keep him happy, clean, and in the end: FLUFFY! One thing we've identified that needs work is getting the boys to, I guess, respect Moshi as an individual, if that makes sense? They adore him but are a bit too rough and don't really know their own limits, let alone a tiny puppy's.
I don't know how old your sons are, but it makes sense that they see Moshi as just the new toy for now. A new (super fluffy!) toy that can't clearly communicate where the boundaries are and that didn't come with a manual. As Moshi grows he will be better able to bark back, but until then, it's up to you and your wife to teach where that boundary is.