Interestingly, in British towns where there is a large Caribbean population, many of the residents from both communities are bi-lingual (bi-dialectical?? maybe not!)

bi-patoisal, perhaps? The facility that children have for linguistic flexibility is one of the traits I most envy them for. Note the raffish, devil-may-care, prepositional end to the preceding sentence. Here in NZ, with the resurgence of Maori, including total immersion schools (in which English is not used or taught at all) from ages two through ten, it is now once again possible to meet eight and nine year olds born and raised here for whom English is very distinctly their second language.