New Duplex w/ tenants and incomplete existing lease

[Adam Kecskes]

I recently purchased a duplex in Texas and already having some troubles with the tenants (three roommates) in one of the units. 

Three major issues:

1) Two of the three tenants are smokers.

2) One of the tenants has a cat (which I knew of going into the deal) and another tenant brought a kitten into the unit (without notifying me or the other tenants, for that matter).

3) Two of the tenants are male and one (the one with seniority on the lease) is female. She didn't have a say in her two roommates (the old landlord just foisted them on her) and she states that she "feels unsafe."

The problem deepens: The old landlord chose to go with a non-standard lease agreement that does not cover the topic either smokers or pets in any way, not even a passing mention (and there's no addendum for either as well).

I want the two male tenants out; I have been told that they are smoking in the house (including marijuana), though at the moment I do not have any personal verification of this (I do know they smoke outside). 

Due to a clause in the existing lease regarding drugs, I think I have grounds to evict, but along with that there is another clause about being considerate of the "rights, comfort, health, safety, or convenience of others." I don't know to what level of evidence I need, but I am headed over there tomorrow for another purpose and will let my nose be by guide.

But rather than evict, I'm pondering simply offering them an out; vacate the dwelling within two weeks and I won't charge them the normal one-months lease-break penalty in the contract. 

I'd love to hear your thoughts and any suggestions on how I might proceed.