On the middle of the upper seat, there is a small half inch cut. How can you stop it from getting bigger?

 

I used this method a couple of years ago on a leather chair and it worked well. Should work just as well on car seats.

 

Get it repaired by a professional, or replace it. Over time anything else will look awful.
Regards,

 

100% perfect seat other then is oddly placed tiny *** rip.

 

Clear nail polish will tide you over till you get it sorted professionally depending on the size of the cut but don't use glue whatever you do ,some products will burn through , I used clear nail polish on a small cut on the seat of a Lether sofa and it still holds

 

I had some worn leather with some minor tears (1-2 inches) in my 93 Corvette. I used some materials from Leather World Tech Car & Auto Leather Repair Kits

The patch is applied with glue to the back side of the leather. After patching and re-dying that area of the seat, it looked like new.
I actually got the color a little better after that picture so that it matched 100% as it took a few more tries. I didn't get a picture of the final color.

I used this same product on my 2002 XKR but I did not have a tear. I just had some wear on the side of the driver's seat. My only complaint is that it is sometimes hard to get the color 100% at first. I usually have to use their tints to get it a little darker. On a gray BMW interior it matched easily.
before:

after