title_body: How would the grammar of a conlang develop as a creole from other languages? Assume that the backstory of a conlang is that it developed from a set of other languages. In other words, speakers of these (different) languages were living in the same area and were communicating with each other and from this a new language emerged, a creole. 
  
  In such a situation which aspects of the original languages would be inherited by the new languages? Obviously the vocabulary would be somewhat mixed but what happens with the grammar? Would the easiest concepts prevail? Would it be necessary that one of the original languages would be dominant in some sense or could they have an equal influence?
upvoted_answer: I would think that it relates to the power structures behind the language communities, and to their relative size.
  
  This can be kind of observed with English after the Norman invasion. The basic English grammar still remained Anglo-Saxon (as the majority of the population spoke it), and the main influence of Norman French (the powerful but small elite) was in the vocabulary. There are a few instances (eg putting some specific adjectives after the noun, as in president elect or times past) where French structures were adopted.
  
  I would think that vocabulary is more a conscious choice, and Norman power made people adopt French words, but the grammatical structures being more sub-conscious meant that they were harder to change.
  
  Another issue is how closely related the origin languages are. Obviously, while Norman French and Old English are different families, they both share the Indo-European ancestry, so are not that radically different. Compare that to, eg the Philippines, where there is a great language variety, and Asian/Polynesian languages clashed with Spanish/English in the colonial period. Here is one creole, Chavacano, which apparently has mostly Spanish vocabulary (so that it is classed as a Romance language), but their grammatical structures are generally similar to other Philippine languages (Wikipedia).
  
  So it seems that power drives the vocabulary, but quantity of speakers determines the grammar.