I proposed something quite similar last week, here.
It would be easy to implement, requiring less than half a column in a chapter where multiclassing is introduced.
This could be easily done, maybe in a separate section like the multiclassing rules in the current PHB.
You could have a table listing the specific features that are gained/lost with mixed parentage: FOR EXAMPLE:
Human -- Versatile (but must take Skilled feat)
Ardling -- Clelestial Legacy
Dragonborn -- Draconic Ancestry and Breath Weapon
Dwarf -- Dwarven Toughness and Darkvision
Elf -- Elven Lineage
Gnome -- Gnomish Cunning
Halfling -- Luck
Orc -- Relentless Endurance
Tiefling -- Fiendish Legacy
So, to use an example of my best friend Rick's halforc/halfling chracter when we were 14, he could be small sized [i.e. building off the halfling], with Brave, Halfling Nimbleness, Naturally Stealthy, and the Orc's Relentless Endurance. (Or he could be medium sized [i.e. based on the orc], with Darkvision, Powerful Build, Adrenaline Rush, and the halfling ability Lucky.).
ps -- to be clear: the proposed list is to show ease of implementation, not to be dogmatic about specific traits represented.
You could have a table listing the specific features that are gained/lost with mixed parentage: FOR EXAMPLE:
Human -- Versatile (but must take Skilled feat)
Ardling -- Clelestial Legacy
Dragonborn -- Draconic Ancestry and Breath Weapon
Dwarf -- Dwarven Toughness and Darkvision
Elf -- Elven Lineage
Gnome -- Gnomish Cunning
Halfling -- Luck
Orc -- Relentless Endurance
Tiefling -- Fiendish Legacy
So, to use an example of my best friend Rick's halforc/halfling chracter when we were 14, he could be small sized [i.e. building off the halfling], with Brave, Halfling Nimbleness, Naturally Stealthy, and the Orc's Relentless Endurance. (Or he could be medium sized [i.e. based on the orc], with Darkvision, Powerful Build, Adrenaline Rush, and the halfling ability Lucky.).
ps -- to be clear: the proposed list is to show ease of implementation, not to be dogmatic about specific traits represented.
It would be easy to implement, requiring less than half a column in a chapter where multiclassing is introduced.