I'm assuming you were at the point of either just adding the eggs, or cooking the mixture on the stove?
When adding eggs to something warmer, the eggs need to be heated first by adding some of the warmer mixture to them.
So how do you prevent the eggs from scrambling when you do that?
: Many thanks, but I think I will stick with the pre-made mixes. Much less risk of burning my house down if I do that.
(This thing with the pudding from scratch - that happened in 1995, and I haven't attempted it since...)