Canadian family 4 year military commitment-Anyone have experience

[Allen Smith]

We have a family that is coming from Canada on a 4 year military commitment. Wanting to lease our home for 4 years. Only problem is getting background check and credit report because they don't have a SS number.  Does anyone have experience? We are impressed with the family. They have a military clause in the contract, basically says if he is reassigned or released from service, they can give 30 days notice to be released from the contract.  Anyone have suggestions-pro's and con's?