Thank you! The care suggestion is a good one, Brodie is a bit inconsistent about when/who he will allow to touch him.
Come to think of it, mine are good at waiting their turn, they just have very different levels of interest & enjoyment from training. Brodie loves tennis balls to the point of obsession, but if I call Jess's name he knows the next throw is for her and won't run for it. They wait for their own food bowl to be filled rather than diving to eat whichever bowl has been filled first etc. But Jess doesn't seem to enjoy training very much and often doesn't really want to participate. I'm not sure if this is just her personality or because I made mistakes - all the training we did when she was younger was entirely treat-based and positive reinforcement, but I was so anxious about wanting her to do well/to be a good trainer that she probably picked up on it. If I leave Jess in the house while I take Brodie into the garden, she will bark at us (whether she can see us or not). If I take her outside and leave her to mooch around while he is getting attention she doesn't bark but does look quite dejected (definitely possible that I am projecting here!) so I thought some reinforcement for her while mooching might make her happy, while he gets rewarded during the training.
There is one issue that I am trying to solve with Brodie that I thought maybe a Treat and Train might help with, though I'm not sure how! When I open the door into the garden he flies out at top speed and does a high speed circuit of the garden, through the back flower bed. This has not been good for the plants, though to reduce the number of plant casualties I have now just left a clear path through that border that he can barrel through. Jess also used to do this and has now stopped - I started making them sit and wait at the open door, while I scattered treats on the grass. Then I would call them to come, with the idea that they would stop to sniff out the treats and thereby get distracted from zooming round the flower beds. This has worked very effectively with Jess and not at all with Brodie, who when released just barrels out the door with even more intensity and does his zoomie before coming to see if Jess has left him any treats. I was wondering if somehow I could incorporate a treat and train into this to try and interrupt Brodie's zoomie circuit and get him to go to a corner of the garden that is not a flower bed. (It's not a big garden, the grass and flower bed area is probably about 30ft square). But I can't really envisage how to do it!
(sorry, very long message!)