So this is just universal stuff. There is no need to flush. You don't even need to spend the extra money on the fancy stuff. I just put Orielley's universal in my Jeeps. It's actually cheaper than the specific stuff. You can mix this with either of them. The headache comes from mixing the two specific ones. That can destroy and engine because they can gel up.
A buddy of mine who runs a small shop, uses universal because farmers do all kinds of wacky things to their vehicles, and then he also doesn't have to stock multiple kinds.
What you really don't want to do is switch from one of the specific to the other. It's just a really bad idea. A shop that tops your vehicle up with the 'correct' coolant could wreck the engine.