My mom has been keeping these white doves for a year an i feel so bad for them i just want to let them go!?

i want them to be free! i feel like they need to fly and mate with other birds i dont feel that its a good thing to keep them... i just recently found out that there both males and the stupid person who sold them to my mm said it was a male and a female. my mom dsnt miss treat them or anything she feeds them and gives attention but i feel bad bcus they look around there cage like they want out! and i would let them out but i tried once when she first got them and they couldn't really fly so i put them back them yesterday i went into the garage w them to see if they can fly i let them out and they were flying but got tired in like 3 seconds so i put them back please i need help! i feel if i let them go they wouldn't know how to find food of the dangerous of cats or dogs eating them bcus they cant really fly