Alternative suggestion. Less currencies, more items.
Idea is: each faction use specific items for limited in-faction use, trading, diplomacy etc. They have value only in that faction and mostly useless for another, in fact - alternative currency for special use. Each faction has their own unique item. Hegemony can use "Special permission chip" item - rare derelict chip, that can not be duplicated, used in domain military systems to determine clearance level before the collapse, currently - mostly symbol of respect. TT can use a "Tri-Tachyon company shares". While LC think their "Sacred relics" have a value. Etc.
How can player get them? Doing missions, trading them on AI cores, NF and other stuff, piracy (rare loot from trade convoys and military detachments), planetary operations, space hulks, etc.
What player can do with them?
1. Sell. There is always someone in mother faction's spacebars ready to buy them at decent price.
2. Increase rep. Similar to AI cores.
3. Sell it to another faction. Even more money, than 1, but decrease rep with mother faction.
4. Buy random BP from the mother faction.
5. Temporary access for military markets and limited amount of purchases, that normally requires a commission.
6. Bribing authorities, if they catch you doing illegal stuff. Will last for long time in that system.
7. Preventing expeditions on your planets for decent period of times.
8. Sending raids from mother faction onto your enemies (if they are also enemies for mother faction).
9. Buying permission to establish a colony in mother-faction system, if you are not commissioned.
10. Etc.
Concept isn't perfect, as it will create a lot of garbage in inventory. And it hard to balance.
Starsector has a somewhat secondary currency called AI cores.
Exactly. Same system here.