If the rule is the same as last year, if the rider is an asset of an EL team the EL team (doesn't have to be the team with whom he's an asset) has priority. Likewise if he's an asset of a PL club (again it doesn't have to be the team with whom he's an asset) the PL team would have priority.
Facebook tonight (after Martin Dixon Talk-in) "Redcar Bears Speedway News given tonight if we cannot find final rider we may not start the season. Hopefully with nearly 2 months till start this wont happen. The search for our final rider is continuing on a daily basis, one was actually a done deal but fell through last minute and this is only worse case scenario. We still have nearly 2 months to go.
There will only be the one programme surely. They won't know who is there on the second day until after the Saturday, so the second programme would just be blank race pages, as they won't be able to print the second programme with all the riders filled in, in time.
Potentially, Newcastle are 'in the same boat,' :
Sun 3 Jul H Plymouth
Sun 17 Jul H Reserved KOC*
Sun 31 Jul H Redcar
9 Jul is SGP at Cardiff and we don't run the Sunday or Monday if we can help it and Sun 24 is the Fours.