Thought one: If you are going melee, I suggest three levels of Lock to get Pact of the Blade instead of two. It lets you use your charisma for you main hand weapon instead of Str or Dex, which is big. Doing 3/9 also gets you better lock spell slots, bumping them both to level 2 while keeping 5th level bard spells.
You can do 2/10, but the best reasons to do that is for an EB build or the Darkness Witch Sight combo which (will work only because you get the Darkness spell as a drow).
If you really want that melee 10 Bard multi-class, I would suggest Paladin or Fighter for a 2/10. Personally I would go Pally since the synergy with Cha is there, and you get 6th level spell slots which you won't with warlock or fighter. 2 in Fighter gets you action surge, which is one of the most powerful abilities in the game.
Regarding race, I would select Half-drow for the warlock build to get the shield or a full drow for anything else to get Perception as a free skill.
Shadowheart: Your plan sounds good. Between your bard and her half cleric, you'll be good. I would do at least 5 cleric though by the end of the build so you can cast 3rd level spells (rather than upcasting the extra slots if you go Ranger). Or you could even do all three with a Cleric 4/ Ranger 5/ Rogue 3 that is a fun multiclass and still keeps you with 2 ASIs, 3rd level spell slots, extra attack, and sneak attack. Plus if you go gloom 5 assassin 3, your first turn in combat is a murder fest.
Wyll: He would make a good Palock if you don't mind another punchy guy. Warlock 3 for pact of the blade and maybe 5 for fireball then Paladin to get extra spell slots, extra attack, dueling fighting style, and the aura(s) which will really help if everyone is up in front wrecking things. I would definitely do Oath of Ancients in that case to provide the magic damage resistance to the team. Between the two auras everyone will have +5 to their saves and take only 1/4 for spells they save against. This one would be optomized by going 5-6 warlock first (whenever you get extra attack in the final version of the game), then at 8 respec to lock 3 pally 5 before building back up either one. 5 Bladelock / 7 Ancients Pally will get you the auras, fireball, and an extra invocation, all of which are great.
Lae: It might be fun to do Eldritch Knight + Arcane Trickster. I haven't seen that before, but it solves both of their problems spell-wise. Which is that they only get a limited spell selection in very specific schools. The schools don't overlap so you actually get access to a wider array between them. Keep in mind that Barbs can't rage and cast spells, so If you do want to go barb/fighter then consider champion or battle-master as they make stronger combos.
