Hi Dave,
Thanks a lot for the quick answer. Just another theoretical question if I may: While your solution works, if I were to have a lot fields I want to keep (like field3), wouldn’t it mean that I need twice as much memory for these on account that I have to store their ‘keep’ values? It would have been nice if it were possible to use field.rand_mode(0) on said fields to just not pass them to the constraint solver, but I’ve tried it and it doesn’t work.