Can you help out my sofa bed?

I'm trying to visualize the space -- will you see it? If not, could you sew a piece and fill with cotton or something along those lines, to exactly fill the spot...?

How about using throw blankets draped strategically over the space to close the gap? Also- amazing price- I love consignment!!

I wish there was a photo. I'm thinking if you put something in there that won't show from the front... is that the idea ? wondering about those pool noodles. from the dollar store?

I have a large sleep chair in my sewing room and I think I know what you are talking about. There is a 6 inch or so gap when I pull it out between the mattress and the back of the chair and I fill that gap with the pillows (not the seat cushion!) that I usually have sitting on the chair when it is closed. I put the pillows for sleeping, usually two, against those decorator pillows and have had no complaints from any of my guests.

I too would love to see a picture but here goes. If you took a piece of foam and a long strip of vinyl the same color as your sofa, now put the foam in the middle and fold the leather over and sew it shut. Noe take this long piece and attach it to the gap

Here is the sofa. Notice the position of the cushions that weren't sat on versus the one that was sat on. See how it sinks down in the front? It's really uncomfortable because you end up resting on the wood in the front. I tried a pool noodle, it just falls through to the ground.

so that side of the cushion is sunken in , not smashed down correct? If that's the case, I'd suggest a board under the cushions, It will make for a firmer seating, but will hold cushions up and prevent them slipping down.