Cats will be very picky about where they sleep. If you love them so much that you want them to sleep next to you, read this.

[edit] Steps

Find a box or cat carrier to make a little "cat cave" for them.
Place it wherever you want them to sleep.
To make it more comfortable, put a pillow or a folded towel inside.
On the first night, leave the flap open so that they feel free to leave if they want to. It may help to put catnip inside the box.
On the second night, place a cat bed in the back of the box (with catnip if needed) and do this for several nights,each night slightly moving the cat bed closer to the exit of the box.
When the cat and their bed are out of the box, remove the box and close it.