Now, however, they have discovered that the 15 year old sister of one of the two adults named in the lease, has been staying there.  

I'm now at the point where I have two applicants that can move in for July and I'm having a tough time choosing between two of them.Application 1 (3 related + 1 friend) - application was submitted first ProsPlenty of income to pay - 5x+2 with great credit (>700)work with a friend who gave a good reference1 attended the same religious institution i did so I'm less inclined to think they would mess up the unit which could be naive 1 year of rental history with no issues paying a fairly higher renthigh job security (family business)Conshigher chance of short term rental - I'm basing this on their young age and the fact they could easily decide to move out on their own2 with bad credit (<600)Young - early twentiesbasement will need to be used as an additional bedroompotential parking issues (4 cars)"kiddish" rooms would need to be repaintedApplication 2 (1 adult + 4 kids)Proshigher chance of long term rental (>3 years) - I say this because the last two locations this person stayed for 3 and 4 years only to leave when the houses were soldfit to the house - in that the rooms are decorated "kiddish" now and don't need to be modified at all ie. repainted, etc)paid same rent for over 7 years w/no issuesCons43% of income to rentBad credit (<600)  - I'm told this is the result of issues with the absentee parentI should also say i have a relative who is a lawyer involved in real estate so he's prepared my lease and helped me out with what can be done legally etc.

I got was I said I wanted for it, and I really did get the one perfect buyer out there for my unit.Plus, come on,  You're an adult who made a decision knowing that you might NOT end up with a bidding war.  

If the lease only states that 1 adult is going to be living in the unit, you may have grounds to evict her for having more people live in the unit than there are on the lease.

I've been in apartments, rental houses and condos all my adult life and I have NEVER bought a shower curtain rod - that was always provided for me and I buy the liner and curtains and rings.  

I told him I am not the Army and we're all adults. lol

You may be able to put limits on the total number of humans allowed in the unit, credit scores above X for each adult, no rude people, people who smell like alcohol at 10AM, smokers, leather-wearers, vegans, etc.  

But, in the adult world there are consequences for not following through on your contract obligations.Calling it going gangsta is a way to put humor into an expensive, bad experience, and taking the mindset that I'm not going to be a victim.  

Also, you could approach this instead of being 4 adult strangers go for two single parent families, which may feel more like a big family in the house than a bunch of strangers.

@Iaroslav Demydovych Without any additional background with evictions and similar type items, I would lean toward the single lady. 3 adult age children could turn that place into a frat house which would cause damage.