"In advance" of what? The opening date for applications?
Substitutions have always been allowed in the PPP within a club.
And as for a "cost penalty!" Would we have ever heard the end of that if the organisers had initiated it?
Nobody HAS to run the PPP. It is just a fell race. And my experience of running it over the last 20+ years is that not many on this Forum were that interested in doing so.