that's a good question, I would look the user manual and buy the same product.
Back in the days, coolant used to be all the same, now they started to have there own product from manufacturer, kind of a trap to make ppl go to there stealer ship to have coolant at over price tags, cause they use a special additive etc.
If they are not the same color I would not mix them. But that's not a general rule. I have seen at work on Diesel engine someone mix the same color coolant, and for a weird reason it turn in to a jello type texture. very bad. I don't think would happen in a normal car, has the veh came from Europe.
without knowing what is already in there, it's going to be hard to say