How about a lamb tagine, I think I'd cut the meat free from the bone and dice. Or a nice lamb casserole. Both are regular slow cooker meals that freeze well. FiL would insist on moussaka. DH would happily gnaw on the roasted bones.
If you do use the bones to make stock, roast them first to get some yummy flavour, chuck an onion, carrot and whatever veg you have in with some rosemary, then pick off the remaining meat, good for hot lamb sarnie and boil the bones. Strain to remove fat. Freezes well.