Burning relationships - what is good form?

My players and I are setting up for our first campaign, and I’m very excited to see these interesting characters in play. Between them, they have these 6 relationships:
A character’s old mentor is travelling with him, urging him to rise to fame, so the mentor himself may be immortalized, as the person who trained that really famous guy.
A character’s father, the warchief of their nomad tribe, who has nothing but disdain for his son, who broke tradition and left their ways behind.
The mother of a character’s child, and who is married to another man, who doesn’t realize the child is not his.
The prostitute that one of the characters is in love with, despite being raised to be culturally and religiously hostile to such a person.
A character’s old sergeant from their time in the army, who knows that the character killed a fellow soldier, and who is coming to deal out justice.
A character’s second-in-command of his smuggling crew, who is also romantically involved with the character, and has her own ideas about what to do with their organization.

What is good practice here, in terms of burning the NPCs? Should I burn all of them completely? None of them? Should I let the smuggler be in charge of burning his second-in-command? Does the game advice me to do something specific?

Your input is very much appreciated.

The ones that are antagonistic to the PCs should get a full burn, and make sure they are stronger and generally better at doing stuff than the PCs – no one likes paying rps for an antagonist who gets defeate in the first encounter. At the very least, I’d give this treatment to the sergeant, and possibly also the disapproving father. The rest you can just improv as the situation dictates.

So you suggest the antagonistic ones. Gotcha. How about the second-in-command? And if we finish the second-in-command, should I burn or, or let the player do it?

I’d suggest that you burn the NPCs all yourself. If you dont want to fully burn them all at the moment, have some play a more minor role until you are ready (just knowing an idea of what they are skilled in may be enough). The characters could not know everything about those they work with/love/hated by, therefore should not (especially beliefs and instincts). If you would like the players to be involved in the process, the characters would probably know recent lifepaths and obvious traits, but its going to remove drama if you let them chart everything. If the players know how an NPC will act and why, it removes chances for you to do the unexpected or to have said NPC disagree with them (not necessarily a fight, just a different ethos). That’s my suggestion, but others might work too.

I’d have the players burn up their own second-in-command unless you really want to.

With the online character burner making it so fast and easy, I’ve been burning up most of my NPC’s and keeping the PDF’s in a Google Drive folder.