Extending analog outputs?

Ok sorry probably not.

You could use a resistor as a load on the TLC and use that to switch a transistor or a FET and then filter that signal but it's a bit messy.

If you want true analogue outputs from a real D/A converter then you would be better off using an I2C D/A, I have seen ones with four in a package. They even did ones with 6 in a package but I haven't seen them for about 20 years now.