Milla I am amazed at the wonderful things you and your Dad (and family?) have done for your rabbits. They don't realise how lucky they are to have come to live with you
You seem to be doing everything right, and hopefully they will begin to be litter trained once they are neutered. It may take a bit of time after they are neutered for all the hormones to settle down, possibly even two/three months, but you will get there.
They are lucky buns to be so well loved