I am afraid you have been given bad advice on stocking. That tank is nowhere near big enough. Unless your angels are a bonded pair one will kill the other. This may be in one month and it may be in 18 - but it is guaranteed. I have no experience with discus but I would expect the strongest angel to treat them in the same way.
The angelfish should be removed ASAP. Angelfish and discus should never be housed together. For one thing, angelfish are more aggressive, but aside from physical aggression there is feeding aggression. This means the angelfish are more determined ("aggressive") feeders and will easily out-compete discus for food. The discus then slowly waste away, and may stop eating all together just from fear.
Silver Dollars need a group of at least six, but (a) there is not sufficient space here for them, and (b) they should never be combined with discus or angeelfish.
To explain more about angelfish, as another member said they may well beecome nasty. Angelfish is a shoaling species, meaning it must have a group, and with angelfish it should never be fewer than five. Two, three or four angelfish will eventually result in a "bully" if one of them is a male and there is another male; the only exception is a bonded male/female pair. Angelfish must select their mates and bond or there will be trouble.
I had a pair of anglefish, male and female in a 55 gallon tanks one grew to 6 inches plus the other over 4 inch plus. They were beautiful fish but aggressive especially at feeding time. They ended up pretty much alone in the tank except a pleco