To follow up on this post, here is how the cot is joined to our bed after one of the railing has been removed.

Every night, I push the cot close to our bed. I put the brakes on for the cot, place a chair between the other side of the cot and the wall (to prevent the cot from even making the slightest move away from the bed frame). Then I place 2 bolsters to fill the up the gap between her mattress and our bed frame.

Put 2 more pillows to cushion the gap. (Our bed frame is slightly lower than the standard bed frame. If we got a bed frame with the standard height, it probably would have been leveled with her mattress.)

Normally if she woke up middle of the night, she would roll over, and snuggle beside me.

In the morning, all the bolsters and pillow will be removed, and we’ll ‘park’ her cot against the wall.