What is a sill panel? Inner cowl panel?
If so, then what you are dealing with is an area where the flange of the floor panel, the rocker panel, and the bottom edge of the inner cowl panel are layered together. They are welded all together at different stages of the build. This makes it a challenge for restoration of this area without removing each of these 3 panels.
Carl, to be fair I did think the panel I was referring to was called a rocker panel here in the US. I am a Brit and we usually call those outer/side sill panels. Interestingly the FAM also refers to it as the 'side sill' so I had tried to stick to their nomenclature. I guess it is also called the rocker panel though.
I am certainly finding it to b e a challenge to find a sequence alright. I am tackling the sill/rocker and floor pans first and then moving out to the inner/outer cowls. the floor pans wrap over the rocker so it seems the rocker may be the first.