Tying additional lights to entryway light -- does that violate any codes?
All is good safety wise and I would say common sense code wise you are good as well.  However, you have now altered that circuit and technically speaking the code says the you, because you have altered this circuit, now you have to bring the entire circuit up to code. Which means you have to replace the circuit breaker in the panel that feeds that circuit with an ark fault breaker; $40 to $50.