Personally, if in your situation, I would simply leave the unopened ones alone until I finished the others. If all are opened, I still believe that I would use them as is, simply due to consistancy.
I have in the past and will probably in the future blend some of a one pound jug into another partial one pounder. I doubt I would ever blend more than that amount. When I do mix, it is plenty thorough, and I generally see nothing adverse about it.
As mentioned be careful and if you mix the whole batch, make sure you work back up to max charges.