Partigyle question - Strong Scottish and a Irish Red?

[davekippen]

I want to put together a partigyle for the upcoming St Patties holiday. Thinking a Strong Scottish ale with first runnings, and an Irish Red with second.

First Grain Bill:
Maris Otter Malt (40.55%)
Vienna (40.55%)
Munich I (7.37%)
Crystal 60 (5.53%)
Special Roast (5.53%)
Chocolate (0.46%)

I then want to add some Melanoidin and/or Carared to the existing mash, let sit for another ~30/40 minutes and run it out for the red.

Questions:
Will the second mash have enough enzyme power to convert added grain?
Do you have any idea how much additional grain I should add to get the red, well, red?

Thanks!

 

[davekippen]

Is there harm in letting the "sparge" sit for another hour? Tannins?