How to get only selected BlendModes

I have a couple of questions about how to make my filters better in their User Interface. I'll start with the first one.

I describe what In run into in a as simple way possible. I am after the principle in the solution, not per se The Solution to this simple problem.

If I want to make a Blend, but only give choices for a couple of Blends, which are NOT continuous (e.g. Screen, Overlay and Difference).
Continuous would also not work I found out, as Remapping an IntSlider in this case does not work.
How do I do that, apart from putting in x Blends (in this case 3), each set fixed to the wanted BlendMode and feeding them into a switch?

With just 3 BlendModes wanted , it could be doable, but if I want 10 BlendModes and that 6 times, it is getting a bit weird.
It would slow down the computation and clutter the working space.

So, what is a good way to do this?
What's more, I'd like the user to see which BlendMode has been selected, so to learn from it.

I have attached a simple filter to show the case I want and of how not to do it

certain BlendModes selected (Forum).ffxml