From OP: “She lives with her two children, a cat and a dog.” The clause defines a list of type children, size of two, relationship: "her children". The correc

From OP: “She lives with her two children, a cat and a dog.” The clause defines a list of type children, size of two, relationship: "her children". The correct punctuation character following a definition is usually : followed by object instantiation. Ideally we would flesh out the full structure to include "lives with" too. lol etc. However we can avoid ambiguity with: "She lives with her two children and a cat and a dog." No need for any funkiness or whatevs. Keep it simple kids! the: "... and a <thing>" idiom can be repeated as much as you like without fiddling with commas.