According to the lease agreement "Tenant shall not UNREASONABLY without consent to Landlord to enter the premise to exhibit the unit to prospective tenants."  

Pro rated rents have been returned but the questions to this would be the following:--My interpretation of the VA laws and based on the tenants consent to either sell/rent so long as it matures their lease means we should be lawfully entitled to all of their deposit as it was used to pay the marketing/upkeep and closing costs of the home.

But what the seller has is a type of contract that requires consent of any assumption of their financing.

If anyone from Montana knows something about it let me know.Specifically, The residential landlord tenant act of 1977 states in section 70-24-321 (F) "Tenant shall conduct oneself and require other persons on the premises with the tenants consent to conduct themselves in a manner that will not disturb the tenants neighbors' peaceful enjoyment of the premises."

Doing so, will preserve your landlord rights better and allow you to make changes without the tenant's consent. 

Yup, it's in there, specified as part of the lease assignment section.The main points seem to be:Not without written consent of Lessor... which will not be unreasonably withheldSo yeah, looks like it's there, but that "unreasonably withheld" is kind of vague.

Later to find out that they moved in their boyfriend/girlfriend without written consent.

Any "repairs or improvements" he made without written consent is a breach of the lease and is grounds for eviction.

@Bill WilliamsNew Mexico is one of about 9 states that has a Community Property right between married couples, which includes ( as I understand it), as stated previously, the home acquired prior to marriage belongs to the individual, not both of you; hence she would have the freedom to sell or mortgage that home anytime, without your consent involved.Any income earned from such a separate property belongs to the individual, but if you choose to share bank accounts and 'commingle' funds, and the house is sold, those proceeds placed into a joint account become community i.e. both of your funds.Community property is acquired by either spouse during marriage, and selling or  encumbrance requires both of your signatures.  

From my research, it is true in most states unless you give the tenants full disclosure beforehand and have their consent in writing or on the lease rules and initialed.