You can find some bricks and thin boards with the same thickness and put them on the ground to cushion the corners of the low bed, which is as high as the other bed.

The height of the big bed and the small bed is different. How can we splice them into the same height? I think you can be here. You can make a fuss about the bed board and make more beds, so you can raise it. Otherwise, you can put a cushion under the bed and put more cushions to make it higher.

This short mattress is filled with something. So you can be the same height. Generally speaking, it is better for children to sleep near the wall, so it is not easy to fall, and it doesn't matter whether it is high or low. As long as you can lean against the wall, he won't fall. And he won't turn over, which is good.

Let me answer the question about what to do if the small bed is too low and the big bed can't get up. If it is online, you can apply for a return. If it is a physical store, it is recommended to consult the sales staff. It's definitely non-refundable. You can exchange it for a style of the right size. If there is no other way, you can only use it alone.