How to get 3.1 to load a 3.5.4 instrument with no complexity in it?

hi i have a fairly simple 3.5.4 instrument and i would like to load it into 3.1. how do i turn it into a v3.1 compatible version, please? there is no inherent complexity to the instrument itself, but i would like to be able to load the same version to both versions without needing to keep two separate versions. or if two separate versions, thats fine, but how do i do them.

If you look at it simply, wouldn’t it be enough to just fill in that diff?
Is that diff structured in a complex way?