No apology necessary. You *were* correct that initialworld.ini only sets the initial faction-faction relations and that OpenSP's m13.ini only sets player-faction ones. I've been out of it too long...

It still is not entirely logical to me, byt apparently when you use OpenSP, the game seems indeed to ignore the faction-faction relations of custom factions.

Too bad, because (in my limited experience) FL servers are far from stable. I had two crashes the last hour, playing alone on my own server, on my own ip-address. The great thing of OpenSP was not having to use a server :
Oh well, I gptta get some sleep now.

Weird... I don't really think I did anything different from you. I only added one new faction as opposed to the six or seven new ones you have. But I didn't even touch m13! I wonder why it worked for me and not you... very strange.

There is a file in the EXE folder called 'newplayer' IIRC, that uses the same encryption as save files. There are some entries in there that affect the Factions' attitudes to each other and the player. Perhaps something here needs changing or adding in?

Vype,

This newplayer.fl seems to be identical (at first sight, that is) to mpnewcharacter.fl , which I actually did overlook! But nevertheless, my factions did work in MP...

Looking closer at mpnewcharacter.fl , I now see a custom factionname that I don't use anymore. It must have been some months ago (I've been out of it for a long period before picking it up again) that I editted this file. It might have nothing to do with it (as my mod did work correctly in MP, as far as I can tell) but nevertheless it's an error, so thanks for bringing this to my attention.

(some minutes later...)

Well, I've updated both files with my new factions' data. Without any result: in MP there's a huge battle right in front of Vlissingen Shipyard, while in OpenSP the Batavian Marine and Goat Riders just ignore each other.

Nevertheless, thanks for coming with this, as I certainly wouldn't have thought about these files!