Which back up RB should i trade for D.Branch.?

Well if he'll do it Foster but, other than that I wouldn't trade any until later you have all must starts try finding someone like Patrick Crayton, or Ronald Curry and James Jones your three WR's should be started every week so don't waste a RB until a little later see if Lewis and Green or Foster have a big 1st game then trade one of them while they're stock is sky high you might be able to land someone better than Branch