Hope you can provide me with one more clarification. I used Red Star Premier Rouge Levure Seche wine yeast originally, and for the starter in mentioned in the above posts. If I add some bakers yeast, will the wine yeast die off, or will I have two different colonies of yeast growing together?
A quick primer on wine yeast -- any wine, beer, or bread yeast will eat sugar in a substance, emitting CO2 and alcohol. Wine yeast is a subset of that group, chosen for it's alcohol tolerance, the pleasing (to humans) aroma and flavors produced, and flocculation (the lees [yeast hulls and fruit solids] compact well). Beer yeast are chosen as they have qualities make good beer, and bread yeast the same for bread. Note that beer and bread yeast have much lower alcohol tolerance, so getting a wine to ferment to completion using them is unlikely. Plus there are probably thousands of strains that are not considered beneficial by humans.
Any wine, beer, or bread yeast will work -- my first wine was rhubarb made with bread yeast. However, if you want a better wine, use wine yeast. These strains (and there are dozens of them) are selected for the properties that make good wine.
Yeast is a living organism, and in recent years I consider that point far more than I did in the past. This is why I make the overnight starter -- the yeast reproduces well in what for it is a more ideal environment than wine. Overnight the starter temperature equalizes to the must, so when adding it to the must, there is little or no temperature shock, like there would be adding a 90+ F starter to a 70 F must.
Commercial wine yeast can be sprinkled on top of the must or stirred in. This works. However, an overnight starter works better, and produces a faster "ignition".
Why is a fast start good? Yeast has a host of competitors who'd LOVE to eat that sugar! Very few, if any, are anything we humans will appreciate. By getting the ferment off to a roaring start, the wine yeast stomps out or even kills it's competitors, so we have a much better chance at a good outcome.
IF you have activity, you do not need to add anything else. Add that starter to the wine and it will probably ferment.