Originally posted by Mishu:

I also modded some of the starter companions to change their sexual interest, but to no avail so far. They all show the changed proposition, but remain as a rival. Intented?

Modding the companions in itself can't turn them into rivals. The correct steps are:

1. Make your changes, but also set their Export target to Mods/YourModname.
2. Keep their dropdown type as Companion.
3. Don't change their relationship slider.
4. Update.
5. Repeat for the rest of the actors.
6. Export.
7. Start a brand new game with your mod active.

If you skipped any of these, that might be the issue. Companions you met or recruited are already baked into your save.

In an existing game, you can use the shell to give the chosen preference tag to companions you have already recruited.

On a side note, you don't need to mod their disposition to romance the characters you like. There's an option in the journal for that. It makes you irresistible to a certain gender or genders, which lets you romance those characters regardless of their canon. This also requires a new game so you can make that choice in the journal.

Did all of that. But these NPCs were always rivals to me (Sheela & Tabitha). Even in ummodded playthroughs. Maybe an issue with traits/playstyle?

There's an option in the journal for that. It makes you irresistible to a certain gender or genders, which lets you romance those characters regardless of their canon.

Ahh, that's what "irresistible" truly means

Sheela always starts as a rival based on your story with her. That part can't be changed through modding since the tag is applied as the story unfolds. But, you can romance her while being a rival and eventually change that through certain story events.

Tabitha being a rival is probably due to losing too much influence with her for one reason or another. If your influence drops too low, any NPC can turn into a rival. But, it's still possible to repair the relationship, though by gaining more influence.

Influence can drop in many ways. Even flirting with someone in the party can lower your relationship with others who see your character in that light.