I agree with JAE, mixing codes can be very tricky. There can be different load factors and safety principles involved. It is not only a question of making a selection in a software.
Also, the Eurocode does, as far as I know, not define a seismic load. Those defining parameters has to come from a national annex. And if you are in an area where Eurocode is applicable then you probably have to use if for the design.
Thomas