Predd, We direct users not use two complete nutrients in the same feeding. That being the Foliage-Pro and Bloom in your case. Using one or the other will work best, based on my knowledge. Use the Mag-Pro as a supplement to the Fol or the Bloom. If you choose to use both the Fol and the Bloom, just be sure to switch over to Bloom for flowering and then use the Mag-Pro as supplement. I've heard many people just use Foliage Pro throughout the entire grow, then use Mag-Pro as a supplement for flowering. This is the simplest and most effective way I have seen thus far, but these are experienced growers. For a little less experience, I would suggest using the Fol, then the bloom with the mag for flowering using our feeding chart.
As to the worries of a calcium deficiency, we supply enough calcium within our complete nutrients for the pant to store a sufficient amount for the grow. With that being said, that is why you see our Mag-Pro with very little calcium and more sulfur. The sulfur will help to increase pungent smells and tastes while making for a denser bud or flower.