Help for a simple replacement

[DarkGD123]

Let's say that I got the start and end offsets of the original file (which the qpckeater gives me because the file names are based on the offsets). We will use 0x800 as a start offset then 0x5E00 as the end offset for this explanation

Now, I want to override "that" part (for example a blz4 file that has either .tr2 or other formats inside of it), but the modified one is a bit off after I inflated/compressed it and doesn't match with the original (a bit less or more than the original offset)

Original: 0x800_0x5E00 Modified part: 0x800_0x5A00 (the end offset is less)

What can we do in this situation?

[nachotacos69]

🤔

[DarkGD123]

Closing due to no response