I always try to make a justification for things that the game does (or just cheat when I really disagree - forced diplomacy ). I figured if this situation was real, the Seleukids would start demanding their old territory back after the war was over, so I didn't invade Judaea.

I doubt I will ever need those ships, but I may build some (probably just one) for roleplaying purposes when I can afford them.

One of the main things I try to do for roleplaying is to keep track of my family lines. It is kind of easy since I always send relatives to work near eachother. Antigonos' elder brother conquered Illyria, so now his family governs Illyria and Epeiros. Antigonos' younger brother (Kalos) followed him into Asia, so now his relatives govern that region. And Antigonos' decendants (which seems to be my smallest branch of the family) is fighting the wars and guarding the borders.