[quote=@TheUnknowable]
[@Game Maker]How would they be higher HP?  My warlock at lvl 3 would have 10+7+7 hp (2 con bonus per level), or 24, and it isn't Draconic.  They would have 26 at lvl 3, and are draconic, and have a higher con modifier than me.
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The way they built their level 1 sorcerer and level 2 warlock was combining the Hit Point Maximum of both classes together which is called stacking and is not allowed, you have to choose the higher of the 2. Stacking is not permitted as a way to add some draw backs to multi-classing. 

And for a level 3 warlock with a constitution modifier of +2 your HP maximum is 12 (assuming you rolled an 8 on your 1d8 roll plus your constitution modifier for each level over 1).