Balancing player backstories can be a real juggling act, but it's also such a rewarding challenge! One approach I love is to create "story hooks" that link their backgrounds together. For example, if one character has a nemesis, maybe another player's past involves being saved by that nemesis, creating an intertwined story without overshadowing anyone.
Also, consider introducing NPCs or plot points that resonate with more than one character's backstory. It not only makes everyone feel included but can also lead to some really dynamic role-playing moments. I remember in one of my campaigns, we had a shared villain that tied into the backstories of two players, leading to an epic showdown that felt personal for both of them!
What kind of themes are you thinking for your campaign? I'd love to hear more about the backstories your players have come up with!