Mindful that they are in it for the very long term, the Andermanni might note (Queen Elizabeth did in ART) that they are wedged between Manticore and another neighbor (the roof and ceiling of the wedge are unclear, and fighting other great powers is expensive.
There are then two other strategic options for expansion:
1) Actual beneficent support to impoverished Verge worlds, notably education. Privately to local governments: We are beneficent Andermanni navy. We have this SD here. You have a LAC whose maneuvering capacity would be enhanced by the addition of oars. We are generously offering to give you quality education, prolong to select people, trade deals, prolong to select people, and...did I mention prolong to select people? We will administer your finances and education, and, yes the President Forever keeps his graft. We spend the rest honestly. Now that you mention it, the education does focus a bit on how much better people are as Andermanni citizens, but first it says how fortunate the people are to be able to support you as a symbol of your world's greatness.
2) We have here large freighters. We outfit them for very long voyages. We give them the best gravimetric sensors that money can buy, mil-grade compensators, and the armament of a battlecruiser, in case "flight" does not work. Their mission is to go out, say, 500, light years, and look for highly desirable worlds, especially ones that appear to have junctions. You don't have to map the junction, just find the systems. These will be future Andermanii colonies. It will take a while, but we will settle a huge empire, not stay at home the way Manticorians do.
