Nah, I’ve had my fingers behind the backing plate and where the current screw holes are, there’s a bit behind there where the screws can go right into if ya know what I mean? The two holes nearest the edges (that I wanted to use) are just that, holes with nothing behind like those other two I mentioned. Plastic is thin on the backing plate and I tried screwing in one of the self tappers into the holes as a trial run and they weren’t secure at all.Not had a chance yet. Old plateholder just fixed to the back plate with a couple of self tappers so was just going to do the same. I saw your comment in other thread about the void. Behind. The self tappers should cope with that in the same way that current one is just left on with a couple. As long as you don't overtighten and pull them through the plastic they should be ok.