As having 1 main that has played through most of the first arc and have switched now to a new main, Dragonbait (Hatchling of Val'Sosi), for the 2nd arc, I can still use (for Dragonbait):
2nd Arc
A2-HP3 "Ancient Battles Unfinished"
A2-HP4 "Visions of Lives Past"
A2-SP1 "Once Upon a Time in Metra" by Joe Cirillo
A2-SP2 "Elements of Faith" by Scott Horn
A2-SP3 "The Horror Within"
A2-SP4 "Long March, Dark Coda"
And for my other 4 secondaries (val'Vasik, Bastard Daughter, Tultipetan dwarf, and Dark-kin brood), I can use all of the modules from the 2nd arc, once I receive the certs and information on them to create and flush them out stats-wise
2nd Arc
A1-HP1 "Into the Blessed Lands"
A2-HP2 "That Which Lies Beneath"
A2-HP3 "Ancient Battles Unfinished"
A2-HP4 "Visions of Lives Past"
A2-SP1 "Once Upon a Time in Metra" by Joe Cirillo
A2-SP2 "Elements of Faith" by Scott Horn
A2-SP3 "The Horror Within"
A2-SP4 "Long March, Dark Coda"