I don't think it can be, even owning a riders contact couldn't be enforced if it went to a court hearing etc. but have previously heard clubs getting warnings for "tapping up" riders, so assume there's some "rule" in place?

No.  How can that be forced with 1 year contracts.   

As this topic has been done to death over the last 18 months.

Unsure but I’ve got ace down at 2.93

There's one rule I'm unsure on, I always thought once a rider averaged above 3.00 they can't drop back down below it. This has been seen with the likes of Adam Roynon averaging below 3 but having a 3 average. But I did see Kyle Bickley drop below 3 when he shouldn't have.    So either the rules have changed, or they've forgotten them, or made mistakes, or ignore them when including British reductions, I'm not sure tbh   Charles Wright 8.37 Erik Riss 8.33 Danny King 7.88 Jason Edwards 6.18 Jake Mulford 4.27 Ace Pijper 3.00 Tom Spencer 2.00 Total 40.03

Well don't look at @Redtruck team, even weaker at the bottom end lol!