I want to change the place of a stray cat ?

she is know in my cousins back yars i want her at my back yare our house isn't that far sometime i see the mother cat in our porch looking for food so i want the mom cats kittens i can't take the mom cuz she is aggresive so the kittens are too young and i want to take them when they r old enough so i want to keep an eye on the little family cuz i can't do that every day when she is in my cousins house so am planing on when the mom is not around i take the kittens and put them in my back yard and i will put food their and water so she wouldn't go back there and she will fallow the smell of her kids and the food she will come see the food ,water her kids and a cozy place and she stays and then i can get close to them every day kittens are know 4 weeks old is my plan a good plan and if not what is a good plan