[ChadO]

I would just get the colors you like and add them to the tank you already have. Based on your water parameters (which are on the edge already for Neos) and the fact that you don't want to have a shrimp only tank, you're really not left with much for options. Given that your existing shrimp are in a planted tank with assorted fish, you'll have some losses due to predators. What are you really out if they somehow manage to interbreed? The likelihood of a large and thriving/growing shrimp colony with the setup you have seems marginal. I'd just add the cool colors that you enjoy watching and go from there.