I have my goats, and I've also got a heap of sheep of all sorts, merinos, poll dorsets, white suffolk and crossbreds. And now damaras. I was keeping them separate from the goats but it has started to be slightly difficult and I am wanting to kick them all out to pasture for the winter, all boys together, all girls together.
So what I did was make up a free standing frame (you can wire it to the fence if you want it more stable), it holds my mineral blocks which the goats need but the sheep arent allowed to have. It can also hold a bowl if you prefer loose minerals. Basically the way it works there is a small platform, the goat either has to climb/jump up there (for the little ones) or the big ones just stand with their feet up there, and they can reach the minerals.
The sheep dont jump up there, although now I have added the damaras to the mix and they are browsers, things could be slightly more interesting lol The rest of the mineral blocks just lie on the ground, since they are formulated for both sheep and goats. Its just the high copper one that goes in the stand.
My grain/pellets is easy enough, the goats are dominant over the sheep so I put the goat feed out into a trough first, the goats chase the sheep away, then I put the sheep feed out in a trough on the other side of the paddock. Sometimes I will close a gate between them if I have slow eaters, until they are done.
We graze sheep on alfalfa (we call it lucerne) all the time - I mean the growing plant, not alfalfa hay. It is safe as long as you fill their bellies up with cereal or grass hay before putting them on the paddock.