So the party composition as far as combat/skills goes looks like:
2 Tanks (Steel and Dok... both high AC and a good deal of HP), one providing more consistent damage, one providing more healing/buffs. Neither one is super skillful (I'm using +5 as a benchmark. Steel has Athletics at +5 and a few more at +4, Dok has Insight and Medicine at +5)
2 Rogues (Silver and the Hornet), the swashbuckler focused around two-weapon fighting, the assassin focused around surprise. Either one, if they can set it up, dealing a good amount of damage. Both are a bit easier to hit and have about 2/3 the hit points of the tanks. Both more skillful than their tank buddies, both stealthy.
1 Wizard [Illusionist] (Soledad). I imagine the character will be mostly focused around battlefield control spells with ranged spell attacks. Not sure if her skills will focus mostly on knowledge/INT-based skills.
I'm probably going to land on a Warlock [Hexblade]... so spamming Eldritch Blast at range with decent damage, add a bit of utility spells and a bunch of face/social skills.
Other classes/subclasses that our party make-up would benefit from:
A Barbarian with either the Totem/Bear or Ancestral Guardian paths. The Ancestral Guardian path would play particularly well with the rogues in the group. The Bear path is super tanky. Play as a Human [Variant] and pick up either Polearm Master, Sentinel or Great Weapon Master (I'd go Sentinel probably). This would give us a tanky defender who makes sure that the enemies pay dearly if they decide to attack anyone but the Barbarian.
A Bard. Any of the subclasses would work. Mostly a support character (rather than direct damage), the bard has lots of buffs and debuffs. Lots of skills, especially if you want to mix social and stealth. Plus a little bit of extra healing between fights. Halfling [Lightfoot], Half-Elf or Human could all work.
A Paladin, especially with either the Conquest or Vengeance subclasses, would work great. Or you could multiclass it with Warlock [Hexblade] and keep it focused around Charisma... so Paladin 2 / Warlock 1 and pick up Eldritch Blast and Booming Blade, plus Hexblade's Curse and Hex and the paladin spell slots to smite would add a good amount of damage. Play as a Half-Elf, Human or maybe an Aasimar (any subrace, though Scourge has the best Warlock/Paladin attribute mix and Fallen has the best attribute mix for a straight Paladin.
A Ranger, especially the Gloom Stalker, would work well. The Gloom Stalker is invisible in darkness to those that use darkvision to see in the darkness. (Free invisibility in the dark, yes please!) The ambusher feature is similar to the Assassin's ability, making the party more likely to want to set you guys up to rain down pain on unsuspecting targets. The Hunter subclass could also work.
I was going to suggest a direct damage sorcerer or wizard, especially one able to soft up multiple targets from range... but that doesn't really come online until 5th level.
Just some thoughts... . Really though, at 7 players, you could play anything.