Dojibear,
In general they should, and for larger moves they do, but you can see some significant variances day to day.
Personally I watch the soymeal contract for the real clues about this market. I consider it to be the primary market. Soybeans are just the parent product, and bean oil is a byproduct.
I keep a jar of soybeans at the desk (along with other commodity decorations) and you'd be surprised, most of the cityfolk don't recognize them and don't have even have a clue what they are. (I suppose I don't help the matter very much by having a couple of ears of a very old strain of corn which most people guess is wheat.) And few people would say they have soymeal in their pantries, not realizing it's in lots of their processed food.
For some reason retail traders like to trade the oil contract, and that makes it difficult for me to trade. You never know when the school of fish is going to change direction. I suppose they like it because it's a little smaller contract, and most people have a bottle of the stuff in the pantry, so they can relate to it.
For large price moves, the crushers will keep the contracts roughly in line with each other. As far as smaller moves go, it's not uncommon to see meal trading lower on the day and oil trading higher. Pay attention to the meal, that's where the money is.