
Sounds to me like not only are they not housetrained, but they are not very interested in HIM and far more interested in one another. Not surprising if they have been brought up together and work hasnt been put in spending time wtih them individually.
Id suggest to him quite strongly that he needs to put in some serious work now, as this also sounds like scent marking and he's likely to have to deal with a power struggle between them as they mature.
Em