You can create a dual class by combining elements of two classes since the beginning. Here's how you do it at first level:
1) choose two classes that no one else chose.
2) choose one package per chosen class from the ones below.
3) stat out your Dualclass merging the tags you find in both packages:
• Moves: you gain the moves listed in both packages. They work normally as they're written in the class' playbook.
• +HP: you gain HP equal to Constitution+the bonus listed in both of your class packages.
• ±Damage: your damage is equal to d6; if you have +damage from one package, it's d8 instead; if you have +damage from both packages, it's d10 instead; however the second wizard package decreases the damage size by one step.
• ±Bond: you gain 4 starting bonds mixed as you wish from the chosen classes. If one package has +bond, choose one more bond; if one package has -bond, choose one less bond.
4) choose an alignment move from one class or the other; you must choose an alignment shared by both classes.
5) choose a racial move from one class or the other; you must choose a race shared by both classes.
When you level up, you select one advanced move from one class or the other. However, by level 5 you must have at least 1 move per class; and by level 10, you must have at least 2 moves per class.
Bard
Package 1: arcane art, +2-HP
Package 2: bardic lore, charming and open, a port in the storm, +bond, +4-HP
Cleric
Package 1: Commune, Cast a Spell, +3-HP
Package 2: Deity, Divine Guidance, Turn Undead, +5-HP
Fighter
Package 1: Bend Bars Lift Gates, Armored, +5-HP, +damage
Package 2: Signature Weapon, +5-HP, +damage
Paladin
Package 1: Armored, I Am The Law, +5-HP, +damage
Package 2: Quest, Lay on Hands, +5-HP, +damage
Ranger
Package 1: Hunt and Track, Called Shot, +5-HP, +damage
Package 2: Animal Companion, Command, +3-HP
Thief
Package 1: Trap Expert, Tricks of the Trade, Flexible Morals, +4-HP
Package 2: Backstab, Poisoner, +2-HP, +damage
Wizard
Package 1: Ritual, +2-HP
Package 2: Spellbook, Prepare Spells, Cast a Spell, Spell Defense, -damage, -bond, +2-HP
Druid
Package 1: Born of the Soil, Shapeshifter, +2-HP
Package 2: Born of the Soil, Studied Essence, By Nature Sustained, Spirit Tongue, +4-HP
Work in Progress:
I don't know how to approach the starting gear selection:
• you just choose your starting gear from one class or the other;
• gear options are included in every pakage and you must choose among them;
• every package gives you N coins worth of gear you can use to buy equipment before the game starts.
If you get the armored move from both of your class packages, what happens? Maybe you just get +1 armor, or more HPs. Or maybe nothing happens.
For the wizard, maybe it would be needed to add a third, simpler package:
Package 3: spellbook, prepare spells, cast a spell, -bond, +2-HP
So that a fighter/wizard does not have its damage reduced.
I was thinking to add an universal advanced move that allows a dual classed character to obtain moves from the packages he didn't choose, but it's a bit tricky and I still have to find a good solution for this.
The logic behind this is just that for each class, its stats are divided in two roughly balanced blocks, which combined result in the original class. But maybe it won't work, and I should just create one package for every class that gives modified versions of its moves to make them work better in this way (exactly like in D&D4's hybrid classes). However, in the near future I will playtest this and if someone is interested I will post the AP.