You may be out of luck on the 'smarter' part
The main difference between sheep and goats is their metabolisims. Sheep are the slugs/sloths of the rumimant world. They do need copper, but in such small amounts because that mouthful of mineral goes so slowly into the bloodsteam, stays forever stored in the liver, that if you give them too much it will quickly become too much, toxic. And why sheep would have longer milk/meat withdrawals of all drugs and wormers also.
Goats are the ahtletes of the ruminant world. Everything, wormers, drugs, antibiotics, vitamins and minerals all speed through their very fast metabolisim. So she needs fresh stores of vitamins and minerals and copper daily, she doesn't store things in her liver as long as other ruminants do. Why some of the drug amounts make our sheep friends and vets cringe.
And the last answer is a big ole NO. Remember that our animals only go to the mineral mix for the salt content, or in some cses the molassas. So if you had some non bitter tasting poision in the mineral mix, you could kill off your entire herd by adding it to the salt in their mineral mix. So you have to keep the sheep mineral away from the goats and vice versa. I would much rather keep a sheep mineral out and keep my goats copper defficient if you can't keep it seperate, and just deal with it, than to kill my sheep. The problem really comes if you live in a defficient area is worms. Your sheep will always carry heavier worm burdens if your goats are nutritionally stressed from being defficient. You will always have problems with your sheep and worms, before the overburden turns into problems with your goats. Yes you could worm more often, but that's a double edged sword, it costs more, you have to handle the goats more often, and you will soon be resistant to the wormer. For me the hoof problems would be my biggest reason for finding a way to feed them seperately, goats with copper defficiency overgrow their hooves, they simply are not as hard, spongy with even dew from the grass. So for me it's about over all herd health, and my hatered of hoof trimming.
Perhaps you could do some sort of jump gate, the goats go over the sheep can't get in because they won't jump? Worked on mine, alas if you have barbados it wouldn't.
Another problem is breeding season, rams will breed does and bucks will breed ewes, giving you no kids/lambs just abortions and open does/ewes the following spring. Vicki
