Procedure for getting STCs through in the UK

[QDMQDMQDM]

I'm going to add a couple of minor STCs to my cub which I know are already present on other UK aircraft (landing gear safety cables and rear cross brace bracket for front shoulder harness, both F. Atlee Dodge STCs). What procedure do I have to go through for this? Do I actually have to find and contact the owners of the G-reg aircraft which have been so modified? Obviously the work will have to be done by an LAE etc.

Anyway, I guess this is one for Genghis or A+C...?

Thanks,

QDM