I have a client, US citizen,   married a Mexican residents that has 2 children.  He maintains 2 households, one in US and one in Mexico.   He travels between the countries for business.   The wife travels with him and is applying for an ITIN.  The children stay in Mexico for educational reasons and are not applying for ITINs.  They are under 17.   

Without ITINs, I see no way for my client to claim these children.   His wife will be on his return and he is filing MFJ.   Am I correct?