Why would they say to their child [creole] 'make milk gone', when they could say [native language] 'drink all your milk'?
Perhaps because the two parents speak different languages to each other with limited overlap, and the kids run around in a social group that draws on perhaps 4 other languages, as a typical example! Young people are always the creative force in language development, and no more so than at the frontiers where different languages collide and recombine. The young people end up teaching their parents a new language, by sheer pressure of efficiency (to take the topic back to its origins).
A short description of the typical process is something like:
1st generation, first step: multiple mother tongues combining in confusion
1st generation, second step: creation of simple pidgin as a mutual language
2nd generation: creation and development of creolized language
later generations: evolution of creole into separate mother tongue
the adults would do the same thing, given enough time together
They do. Just observe the workings of this virtual speech community, with its rapid accretion of 'insider' code!
