Yes as Ray said the rule of thumb (and a very good very stern rule) is to NEVER combine components from different manufacturers. Unless you are VERY well versed you don't even use a reducer other than the one in you tech sheet for the product you are using. There are reducers containing things that aren't in a "regular" reducer needed for the product you are spraying. This is most certainly not always true and using a quality urethane reducer from another company isn't going to hurt a thing, unless you are VERY WELL versed in the facts of the product NEVER DO IT.
Some products are even relabeled and sold under different brand names so of course they would be exactly the same. But without VERY GOOD inside knowledge you have no idea.
As my general rule goes "FOLLOW THE TECH SHEETS"
On your "blender" I am not sure if what you are after but there is no "Blender" for the base coat that I know of in any brand. There are many who use a "colorless" basecoat, you spray it out over the panel before you blend the color out and it helps the metal lay properly for a nicer blend. Or mix it with the color to help blend. http://www.sherwin-automotive.com/me...ish/AS2839.pdf
The "blender" solvent is still used for open blends with clear or a SS color, not a bc/cc. This would be where you are leaving a blend, a real blend at the end of where you are clearing, say up a roof pillar. http://www.sherwin-automotive.com/pr...m?product=BS10
But the basecoat blend isn't like that at all, it will be protected under the clear that you spray over it.
Does this make sense or are you referring to something else?