I don't think Diamond is SO fat that he needs a grazing muzzle, I don't think he's THAT out of shape either. Not anymore then a couple of mine. I think you should talk to that girl though and tell her that you really would rather just ride your own horse for the road rides. Does she have an issue w/ not trusting Diamond? He's the one you said is bombproof isn't he? The bay? He's fat, but not obese. I wouldnt take his grass away, although... How tall and how lush is that grass? I think he's just an easy keeper...
"Be a best friend, tell the truth, and overuse I love you
Go to work, do your best, don't outsmart your common sense
Never let your prayin knees get lazy
And love like crazy"