House hacking sfh lease terms

[Alan De la rosa zamora]

Hello fellow Bp members! I recently acquired my first sfh to house hack and I'm currently doing the screening process with perspective tenants. The house has 6 rooms and ill be renting out the other 5 bedrooms. Since there's gonna be 5 different people moving in I've offered to do a "trial period" of 1-2 months to see if they will be a good roommate/tenant and so they can have peace of mind that they won't have to live with awful roommates they aren't familiar with for a whole year. My questions are regarding the deposit and how to structure the lease. 

Can i tell them that if they dont end up signing the 12 month lease at the end of the trial period that i can keep their deposit in order to get the vacancy filled after they leave? 

Would i need to make them sign two different leases if they do decide to stay(month to month lease then 12 month lease after trial)? Or can i just modify the 12 month lease to include the 1-2 month trial period in the terms of the lease?

Thanks for the advice in advance!