I'm still struggling a bit.
I understand muscle meat is high in phospherous but low in calcium, yes?
So now I'm worried that they're not having enough bone, just what's in the minces and the fish.

One small breahthrough tho'....I've got one of the dogs to eat chicken wings.

Have you tried feeding liver at the same time as bone? It can soften stools, they seem to sort of balance each other. Good news that has eaten chicken bones, softer bones seem to be the way to go (Cain always has hard white stools after lamb bones). Whole rabbit is very good too if you can get it, Cain produces perfect poos, never hard.

Or you could look at feeding a complete food like Natural Instinct? Or I think Raw2Go have the 10% bone already in the mince

Oh thank you Moons Mum for pointing out Raw2Go has 10%bone in their mince.
I've been running down the dogs freezer ready to place my 1st order with them, but I hadn't seen the page giving the actual ratio of meat/bone/offal.

I do feed liver/kidney/heart/lites but the dogs won't eat a meal of purely offal so I add a small amount daily to their other meals.

I did look at adding Bonemeal to substitute the lack of bones, but I read quite a few negative comments on-line about using bonemeal.

I feel a bit more positive now, so I'll be ordering from Raw2Go and then, in a few months maybe I will tentatively try Doug with a bone again.
What scared me was the vet said 'no more bones EVER' giving the impression that Doug has a predisposition to 'not being able to digest bones'. I'd hate to see him in the state he was in last December, poor boy.

Thanks again for your help.