about lease option contract

[Nilo Gabales Samson]

hello biggerpockets community. i would like to purchase a house but the owner agreed on a lease purchase with a 3 year balloon. so my plan is to sublease the property to another tenant buyer at a higher price, my plan is to tell the owner that i need to find my tenant buyer that we might both agreed first before making the monthly payments. My question is that, do i have a time allowance to find my tenant buyer before executing our deal? what if it took me a couple of months to find the right tenant/buyer. will our contract be void? is the owner even though we have a deal can breach it and offer it to another buyer? how can i protect myself from buyers that will go directly to the owner and remove me as the middle man?? your reply for these questions will really enlighten me about my doubts for my first deal. thanks by the way. :)