First idea is pretty simple if you want it to be, make a manufacturing project along the ruleset guidelines, put 2 strange creatures of whatever type as input and 3+ as output.
Or, if you want it more complicated, you could set up a random production system, outputting only 1(net loss), 2(failed breeding, 3(successful breeding), 4(extra successful breeding).
The second idea needs to be clarified first. What exactly do you mean by a blood donation system?