The reason that no one has responded to your thread is that no one wants to be responsible for damage to your Blue Rugs. There are several products on the market that claim to control grassy weeds "over the top" of ornamental plants, Fertilome Ornamec being one of them. The problem is that often there is some damage to the good plant that you don't want to harm.
If you can, using rubber gloves and glyphosate (Roundup) "wick" the grassy weeds by mixing a strong solution of glyphosate and using a rag, wipe and smear the product on the grassy weeds by hand without dampening the juniper. May want to put newspaper over the juniper and lay the grassy weeds on top until the glyphosate dries. This is best done when the juniper is no longer producing new growth, say in the heat of summer. Make sure that the bed has previously been watered heavily to promote growth in the grassy weeds.
Hope this isn't too much work, but by golly, may be the only way to do it without damage to the Blue Rugs.
Hortster

Good to read this thread! I've got Blue Rug on a small slope behind an outbuilding that is also home to broomsedge and yellow jasmine... real pains here in this part of South Carolina. I'm resigned to just pulling them out periodically, usually after it rains. I'd considered one of the weed killers that claim not to hurt ornamentals, but didn't trust them enough to try. Good to know my suspicions were correct! (Besides, I think only black magic would get rid of the jasmine here!)

The short answer to your question is NO :-) There is not a single product that will accomplish both tasks. However, once you have successfully removed existing weeds (manually or through other means), an application of corn gluten meal will prevent new weed seeds from germinating AND provide a low nutrient supplement. CGM is only a pre-emergent weed control, so existing weeds must be address by other means first.

A good layer of a coarse textured mulch around and under the junipers (avoid the woody portions) will also help to keep weeds under control. FWIW, junipers require little, if any, fertilizing.

Mulch is your friend with Blue Rug and it stops weeds.